A tough thing about writing is knowing the effect of your words on the unseen reader.
He or she is going to assign meaning to everything you write down. If you wrote it, it must be important, right? Otherwise, why are you making us read it?
An example of this is setting up without paying off. What seems like idle banter to you is going to be regarded by the reader as something worth remembering. o, if you have a guy say to his buddy, “You going to Jeff’s kegger tonight?” “Yeah, buddy, gonna be a blowout.”… and then don’t take us to the party… we’re going to feel left out.
If you have a football game where the hero’s team gets crushed, and the coach tells them, “We meet those bums one more time before season’s end,” we’re going to be expecting to see that final game and either get revenge or not. But, don’t set up that rivalry and expected rematch and then move your hero to the Bahamas for a steel drum festival for the rest of the movie.
If you tell us to expect something, consider very hard before you decide not to deliver it.