"At the end of a story or novel I most artfully concentrate for the reader an impression of the entire work, and therefore must casually mention something about those whom I have already presented." Chekhov
I butcher this by saying, "Don't forget your stuff," and "Your final image already exists in the story. Find it," and "You've invested in the creation of an arresting image. Get a return on that investment. Bring it back and back again." I talk about leaving stains on the reader's mind. Stains are good. And if you've created a strong image, let it haunt.
I talk about two plotting techniques I've come up with, ones I see again and again.
Hint, circle, reveal.
Reveal, circle, hint.
In the first, the author mentions something larger, but only a hint, then circles back to it, and then finally reveals.
In the second, they tell everything, then circle it with an image, and then make one deft final mention.
These sound like rules. There are no rules. Only things you can try to get away with.