diff --git a/src/internal/observable/combineLatest.ts b/src/internal/observable/combineLatest.ts
index c573f02c8e4..b207405fe9e 100644
--- a/src/internal/observable/combineLatest.ts
+++ b/src/internal/observable/combineLatest.ts
@@ -10,6 +10,7 @@ import { popResultSelector, popScheduler } from '../util/args';
 import { createObject } from '../util/createObject';
 import { OperatorSubscriber } from '../operators/OperatorSubscriber';
 import { AnyCatcher } from '../AnyCatcher';
+import { executeSchedule } from '../util/executeSchedule';
 
 // combineLatest(any)
 // We put this first because we need to catch cases where the user has supplied
@@ -293,7 +294,7 @@ export function combineLatestInit(
  */
 function maybeSchedule(scheduler: SchedulerLike | undefined, execute: () => void, subscription: Subscription) {
   if (scheduler) {
-    subscription.add(scheduler.schedule(execute));
+    executeSchedule(subscription, scheduler, execute);
   } else {
     execute();
   }
diff --git a/src/internal/operators/bufferTime.ts b/src/internal/operators/bufferTime.ts
index f7af350fc49..cab6dd2b21e 100644
--- a/src/internal/operators/bufferTime.ts
+++ b/src/internal/operators/bufferTime.ts
@@ -5,6 +5,7 @@ import { OperatorSubscriber } from './OperatorSubscriber';
 import { arrRemove } from '../util/arrRemove';
 import { asyncScheduler } from '../scheduler/async';
 import { popScheduler } from '../util/args';
+import { executeSchedule } from '../util/executeSchedule';
 
 /* tslint:disable:max-line-length */
 export function bufferTime<T>(bufferTimeSpan: number, scheduler?: SchedulerLike): OperatorFunction<T, T[]>;
@@ -117,21 +118,18 @@ export function bufferTime<T>(bufferTimeSpan: number, ...otherArgs: any[]): Oper
           subs,
         };
         bufferRecords.push(record);
-        subs.add(scheduler.schedule(() => emit(record), bufferTimeSpan));
+        executeSchedule(subs, scheduler, () => emit(record), bufferTimeSpan);
       }
     };
 
-    bufferCreationInterval !== null && bufferCreationInterval >= 0
-      ? // The user passed both a bufferTimeSpan (required), and a creation interval
-        // That means we need to start new buffers on the interval, and those buffers need
-        // to wait the required time span before emitting.
-        subscriber.add(
-          scheduler.schedule(function () {
-            startBuffer();
-            !this.closed && subscriber.add(this.schedule(null, bufferCreationInterval));
-          }, bufferCreationInterval)
-        )
-      : (restartOnEmit = true);
+    if (bufferCreationInterval !== null && bufferCreationInterval >= 0) {
+      // The user passed both a bufferTimeSpan (required), and a creation interval
+      // That means we need to start new buffers on the interval, and those buffers need
+      // to wait the required time span before emitting.
+      executeSchedule(subscriber, scheduler, startBuffer, bufferCreationInterval, true);
+    } else {
+      restartOnEmit = true;
+    }
 
     startBuffer();
 
diff --git a/src/internal/operators/mergeInternals.ts b/src/internal/operators/mergeInternals.ts
index fc7d1a613e7..be995949389 100644
--- a/src/internal/operators/mergeInternals.ts
+++ b/src/internal/operators/mergeInternals.ts
@@ -2,6 +2,7 @@ import { Observable } from '../Observable';
 import { innerFrom } from '../observable/from';
 import { Subscriber } from '../Subscriber';
 import { ObservableInput, SchedulerLike } from '../types';
+import { executeSchedule } from '../util/executeSchedule';
 import { OperatorSubscriber } from './OperatorSubscriber';
 
 /**
@@ -114,7 +115,11 @@ export function mergeInternals<T, R>(
                 // Particularly for `expand`, we need to check to see if a scheduler was provided
                 // for when we want to start our inner subscription. Otherwise, we just start
                 // are next inner subscription.
-                innerSubScheduler ? subscriber.add(innerSubScheduler.schedule(() => doInnerSub(bufferedValue))) : doInnerSub(bufferedValue);
+                if (innerSubScheduler) {
+                  executeSchedule(subscriber, innerSubScheduler, () => doInnerSub(bufferedValue));
+                } else {
+                  doInnerSub(bufferedValue);
+                }
               }
               // Check to see if we can complete, and complete if so.
               checkComplete();
diff --git a/src/internal/operators/observeOn.ts b/src/internal/operators/observeOn.ts
index 049c8b03268..2c27dbcec9d 100644
--- a/src/internal/operators/observeOn.ts
+++ b/src/internal/operators/observeOn.ts
@@ -1,5 +1,6 @@
 /** @prettier */
 import { MonoTypeOperatorFunction, SchedulerLike } from '../types';
+import { executeSchedule } from '../util/executeSchedule';
 import { operate } from '../util/lift';
 import { OperatorSubscriber } from './OperatorSubscriber';
 
@@ -57,51 +58,12 @@ import { OperatorSubscriber } from './OperatorSubscriber';
  */
 export function observeOn<T>(scheduler: SchedulerLike, delay = 0): MonoTypeOperatorFunction<T> {
   return operate((source, subscriber) => {
-    /**
-     * Executes work with the provided scheduler and provided delay.
-     * This exists primarily to manage the Actions being scheduled to make
-     * sure they are removed from the parent Subscription.
-     * Actions will be retained in memory until the parent Subscription finalizes
-     * because they could be rescheduled at any time. We know the
-     * actions in this operator are NOT going to be rescheduled, so
-     * we want to make sure they're removed as soon as possible.
-     * @param execute The work to schedule with the scheduler provided
-     */
-    const schedule = (execute: () => void) => {
-      let syncUnsub = false;
-      const actionSubs = scheduler.schedule(() => {
-        if (actionSubs) {
-          // The action fired asynchronously, so we have a subscription
-          // we can unsubscribe before continuing. Unsubscription will
-          // remove the Action/Subscription from the parent (subscriber).
-          actionSubs.unsubscribe();
-        } else {
-          // The action fired synchronously, so we don't have a
-          // subscription we can unsubscribe just yet. Flag that
-          // we want to unsubscribe when we do get it.
-          syncUnsub = true;
-        }
-        // Execute the work required.
-        execute();
-      }, delay);
-
-      if (syncUnsub) {
-        // The action above fired synchronously, so we can tear it down.
-        actionSubs.unsubscribe();
-      } else {
-        // The action hasn't fired yet. It's asynchronous. So we should
-        // add it to our subscriber, which is the parent Subscription,
-        // so it is unsubscribed if our consumer unsubscribes.
-        subscriber.add(actionSubs);
-      }
-    };
-
     source.subscribe(
       new OperatorSubscriber(
         subscriber,
-        (value) => schedule(() => subscriber.next(value)),
-        () => schedule(() => subscriber.complete()),
-        (err) => schedule(() => subscriber.error(err))
+        (value) => executeSchedule(subscriber, scheduler, () => subscriber.next(value), delay),
+        () => executeSchedule(subscriber, scheduler, () => subscriber.complete(), delay),
+        (err) => executeSchedule(subscriber, scheduler, () => subscriber.error(err), delay)
       )
     );
   });
diff --git a/src/internal/operators/timeout.ts b/src/internal/operators/timeout.ts
index 8e33cde9b20..1d17e40a845 100644
--- a/src/internal/operators/timeout.ts
+++ b/src/internal/operators/timeout.ts
@@ -6,8 +6,8 @@ import { operate } from '../util/lift';
 import { Observable } from '../Observable';
 import { innerFrom } from '../observable/from';
 import { createErrorClass } from '../util/createErrorClass';
-import { caughtSchedule } from '../util/caughtSchedule';
 import { OperatorSubscriber } from './OperatorSubscriber';
+import { executeSchedule } from '../util/executeSchedule';
 
 export interface TimeoutConfig<T, O extends ObservableInput<unknown> = ObservableInput<T>, M = unknown> {
   /**
@@ -342,18 +342,22 @@ export function timeout<T, O extends ObservableInput<any>, M>(
     // tell how many values we have seen so far.
     let seen = 0;
     const startTimer = (delay: number) => {
-      timerSubscription = caughtSchedule(
+      timerSubscription = executeSchedule(
         subscriber,
         scheduler,
         () => {
-          originalSourceSubscription.unsubscribe();
-          innerFrom(
-            _with!({
-              meta,
-              lastValue,
-              seen,
-            })
-          ).subscribe(subscriber);
+          try {
+            originalSourceSubscription.unsubscribe();
+            innerFrom(
+              _with!({
+                meta,
+                lastValue,
+                seen,
+              })
+            ).subscribe(subscriber);
+          } catch (err) {
+            subscriber.error(err);
+          }
         },
         delay
       );
diff --git a/src/internal/operators/windowTime.ts b/src/internal/operators/windowTime.ts
index d5c8354b126..4301e616ad4 100644
--- a/src/internal/operators/windowTime.ts
+++ b/src/internal/operators/windowTime.ts
@@ -7,6 +7,7 @@ import { operate } from '../util/lift';
 import { OperatorSubscriber } from './OperatorSubscriber';
 import { arrRemove } from '../util/arrRemove';
 import { popScheduler } from '../util/args';
+import { executeSchedule } from '../util/executeSchedule';
 
 export function windowTime<T>(windowTimeSpan: number, scheduler?: SchedulerLike): OperatorFunction<T, Observable<T>>;
 export function windowTime<T>(
@@ -136,21 +137,18 @@ export function windowTime<T>(windowTimeSpan: number, ...otherArgs: any[]): Oper
         };
         windowRecords.push(record);
         subscriber.next(window.asObservable());
-        subs.add(scheduler.schedule(() => closeWindow(record), windowTimeSpan));
+        executeSchedule(subs, scheduler, () => closeWindow(record), windowTimeSpan);
       }
     };
 
-    windowCreationInterval !== null && windowCreationInterval >= 0
-      ? // The user passed both a windowTimeSpan (required), and a creation interval
-        // That means we need to start new window on the interval, and those windows need
-        // to wait the required time span before completing.
-        subscriber.add(
-          scheduler.schedule(function () {
-            startWindow();
-            !this.closed && subscriber.add(this.schedule(null, windowCreationInterval));
-          }, windowCreationInterval)
-        )
-      : (restartOnClose = true);
+    if (windowCreationInterval !== null && windowCreationInterval >= 0) {
+      // The user passed both a windowTimeSpan (required), and a creation interval
+      // That means we need to start new window on the interval, and those windows need
+      // to wait the required time span before completing.
+      executeSchedule(subscriber, scheduler, startWindow, windowCreationInterval, true);
+    } else {
+      restartOnClose = true;
+    }
 
     startWindow();
 
diff --git a/src/internal/scheduled/scheduleAsyncIterable.ts b/src/internal/scheduled/scheduleAsyncIterable.ts
index ffadfbf2937..b5b44abffe0 100644
--- a/src/internal/scheduled/scheduleAsyncIterable.ts
+++ b/src/internal/scheduled/scheduleAsyncIterable.ts
@@ -1,28 +1,32 @@
 import { SchedulerLike } from '../types';
 import { Observable } from '../Observable';
 import { Subscription } from '../Subscription';
+import { executeSchedule } from '../util/executeSchedule';
 
 export function scheduleAsyncIterable<T>(input: AsyncIterable<T>, scheduler: SchedulerLike) {
   if (!input) {
     throw new Error('Iterable cannot be null');
   }
-  return new Observable<T>(subscriber => {
-    const sub = new Subscription();
-    sub.add(
-      scheduler.schedule(() => {
-        const iterator = input[Symbol.asyncIterator]();
-        sub.add(scheduler.schedule(function () {
-          iterator.next().then(result => {
+  return new Observable<T>((subscriber) => {
+    executeSchedule(subscriber, scheduler, () => {
+      const iterator = input[Symbol.asyncIterator]();
+      executeSchedule(
+        subscriber,
+        scheduler,
+        () => {
+          iterator.next().then((result) => {
             if (result.done) {
+              // This will remove the subscriptions from
+              // the parent subscription.
               subscriber.complete();
             } else {
               subscriber.next(result.value);
-              this.schedule();
             }
           });
-        }));
-      })
-    );
-    return sub;
+        },
+        0,
+        true
+      );
+    });
   });
 }
diff --git a/src/internal/scheduled/scheduleIterable.ts b/src/internal/scheduled/scheduleIterable.ts
index 71c3ff17d3d..4b1e1d3fdcf 100644
--- a/src/internal/scheduled/scheduleIterable.ts
+++ b/src/internal/scheduled/scheduleIterable.ts
@@ -2,7 +2,7 @@ import { Observable } from '../Observable';
 import { SchedulerLike } from '../types';
 import { iterator as Symbol_iterator } from '../symbol/iterator';
 import { isFunction } from '../util/isFunction';
-import { caughtSchedule } from '../util/caughtSchedule';
+import { executeSchedule } from '../util/executeSchedule';
 
 /**
  * Used in {@link scheduled} to create an observable from an Iterable.
@@ -16,15 +16,25 @@ export function scheduleIterable<T>(input: Iterable<T>, scheduler: SchedulerLike
     // Schedule the initial creation of the iterator from
     // the iterable. This is so the code in the iterable is
     // not called until the scheduled job fires.
-    subscriber.add(
-      scheduler.schedule(() => {
-        // Create the iterator.
-        iterator = (input as any)[Symbol_iterator]();
+    executeSchedule(subscriber, scheduler, () => {
+      // Create the iterator.
+      iterator = (input as any)[Symbol_iterator]();
+
+      executeSchedule(
+        subscriber,
+        scheduler,
+        () => {
+          let value: T;
+          let done: boolean | undefined;
+          try {
+            // Pull the value out of the iterator
+            ({ value, done } = iterator.next());
+          } catch (err) {
+            // We got an error while pulling from the iterator
+            subscriber.error(err);
+            return;
+          }
 
-        // Schedule the first iteration and emission.
-        caughtSchedule(subscriber, scheduler, function () {
-          // Pull the value out of the iterator
-          const { value, done } = iterator.next();
           if (done) {
             // If it is "done" we just complete. This mimics the
             // behavior of JavaScript's `for..of` consumption of
@@ -34,13 +44,12 @@ export function scheduleIterable<T>(input: Iterable<T>, scheduler: SchedulerLike
           } else {
             // The iterable is not done, emit the value.
             subscriber.next(value);
-            // Reschedule. This will cause this function to be
-            // called again on the same scheduled delay.
-            this.schedule();
           }
-        });
-      })
-    );
+        },
+        0,
+        true
+      );
+    });
 
     // During teardown, if we see this iterator has a `return` method,
     // then we know it is a Generator, and not just an Iterator. So we call
diff --git a/src/internal/scheduled/scheduleObservable.ts b/src/internal/scheduled/scheduleObservable.ts
index 97d6c0d5707..0e724f5a1fe 100644
--- a/src/internal/scheduled/scheduleObservable.ts
+++ b/src/internal/scheduled/scheduleObservable.ts
@@ -1,19 +1,8 @@
-import { Observable } from '../Observable';
-import { Subscription } from '../Subscription';
-import { observable as Symbol_observable } from '../symbol/observable';
-import { InteropObservable, SchedulerLike, Subscribable } from '../types';
+import { innerFrom } from '../observable/from';
+import { observeOn } from '../operators/observeOn';
+import { subscribeOn } from '../operators/subscribeOn';
+import { InteropObservable, SchedulerLike } from '../types';
 
 export function scheduleObservable<T>(input: InteropObservable<T>, scheduler: SchedulerLike) {
-  return new Observable<T>(subscriber => {
-    const sub = new Subscription();
-    sub.add(scheduler.schedule(() => {
-      const observable: Subscribable<T> = (input as any)[Symbol_observable]();
-      sub.add(observable.subscribe({
-        next(value) { sub.add(scheduler.schedule(() => subscriber.next(value))); },
-        error(err) { sub.add(scheduler.schedule(() => subscriber.error(err))); },
-        complete() { sub.add(scheduler.schedule(() => subscriber.complete())); },
-      }));
-    }));
-    return sub;
-  });
+  return innerFrom(input).pipe(subscribeOn(scheduler), observeOn(scheduler));
 }
diff --git a/src/internal/scheduled/schedulePromise.ts b/src/internal/scheduled/schedulePromise.ts
index 00da90278bb..e04b7a10f64 100644
--- a/src/internal/scheduled/schedulePromise.ts
+++ b/src/internal/scheduled/schedulePromise.ts
@@ -1,22 +1,8 @@
-import { Observable } from '../Observable';
+import { innerFrom } from '../observable/from';
+import { observeOn } from '../operators/observeOn';
+import { subscribeOn } from '../operators/subscribeOn';
 import { SchedulerLike } from '../types';
 
 export function schedulePromise<T>(input: PromiseLike<T>, scheduler: SchedulerLike) {
-  return new Observable<T>((subscriber) => {
-    return scheduler.schedule(() =>
-      input.then(
-        (value) => {
-          subscriber.add(
-            scheduler.schedule(() => {
-              subscriber.next(value);
-              subscriber.add(scheduler.schedule(() => subscriber.complete()));
-            })
-          );
-        },
-        (err) => {
-          subscriber.add(scheduler.schedule(() => subscriber.error(err)));
-        }
-      )
-    );
-  });
+  return innerFrom(input).pipe(subscribeOn(scheduler), observeOn(scheduler));
 }
diff --git a/src/internal/util/caughtSchedule.ts b/src/internal/util/caughtSchedule.ts
deleted file mode 100644
index 5ff9bdcd4ca..00000000000
--- a/src/internal/util/caughtSchedule.ts
+++ /dev/null
@@ -1,20 +0,0 @@
-import { Subscriber } from '../Subscriber';
-import { Subscription } from '../Subscription';
-import { SchedulerAction, SchedulerLike } from '../types';
-
-export function caughtSchedule(
-  subscriber: Subscriber<any>,
-  scheduler: SchedulerLike,
-  execute: (this: SchedulerAction<any>) => void,
-  delay = 0
-): Subscription {
-  const subscription = scheduler.schedule(function () {
-    try {
-      execute.call(this);
-    } catch (err) {
-      subscriber.error(err);
-    }
-  }, delay);
-  subscriber.add(subscription);
-  return subscription;
-}
diff --git a/src/internal/util/executeSchedule.ts b/src/internal/util/executeSchedule.ts
new file mode 100644
index 00000000000..1bcb9900ff9
--- /dev/null
+++ b/src/internal/util/executeSchedule.ts
@@ -0,0 +1,44 @@
+import { Subscription } from '../Subscription';
+import { SchedulerAction, SchedulerLike } from '../types';
+
+export function executeSchedule(
+  parentSubscription: Subscription,
+  scheduler: SchedulerLike,
+  work: () => void,
+  delay: number,
+  repeat: true
+): void;
+export function executeSchedule(
+  parentSubscription: Subscription,
+  scheduler: SchedulerLike,
+  work: () => void,
+  delay?: number,
+  repeat?: false
+): Subscription;
+
+export function executeSchedule(
+  parentSubscription: Subscription,
+  scheduler: SchedulerLike,
+  work: () => void,
+  delay = 0,
+  repeat = false
+): Subscription | void {
+  const scheduleSubscription = scheduler.schedule(function (this: SchedulerAction<any>) {
+    work();
+    if (repeat) {
+      parentSubscription.add(this.schedule(null, delay));
+    } else {
+      this.unsubscribe();
+    }
+  }, delay);
+
+  parentSubscription.add(scheduleSubscription);
+
+  if (!repeat) {
+    // Because user-land scheduler implementations are unlikely to properly reuse
+    // Actions for repeat scheduling, we can't trust that the returned subscription
+    // will control repeat subscription scenarios. So we're trying to avoid using them
+    // incorrectly within this library.
+    return scheduleSubscription;
+  }
+}