Chekhov's Gun

Remove everything that has no relevance to the story. It's wrong to make promises you don't mean to keep.
~ Anton Chekhov

If you see a rifle on the wall in the first act, it should go off by the end of the play.

I've been waiting and waiting and waiting...

Don’t wait too long to be happy.

Rose to Dr. Benjamin in The Marvelous Mrs. Maisel