This maxim is best remembered in the words of Anton Chekhov, who gave the advice several times and in different ways, one of which is this:
If you say in the first chapter that there is a rifle hanging on the wall, in the second or third chapter it absolutely must go off. If it’s not going to be fired, it shouldn’t be hanging there.—Anton Chekhov
☐ No plant w/out payoff or vice versa.
Whatever your thing is, if it seems important to the reader, it had better, at some point, be important to the story.
Rowling did this well in the Harry Potter series with a lot of things, including the horcrux marked R.B. (For those of you unfamiliar with the story, all you need to know is that a horcrux is an object, a MacGuffin, almost. But not quite.) When it’s first found, it has its own story purpose, and you don’t think too much about the initials. You figure she’ll explain later. And several books later, when she does, it all fits together satisfactorily. It’s doubly satisfying if you figure out who R.B. is before the reveal.
What would have been a problem is if there had been no follow-up on the initials R.B. That would have been plant without payoff, just as Chekhov warned against. These kinds of things should either be deleted in editing, or given a bigger role to play.
One notable exception to this guideline is in mysteries, where you can often plant false clues, known in the trade as red herrings. But even they serve a story purpose, that being to send the investigator—and hopefully the reader—in the wrong direction. But even a red herring needs to be relevant to the story. Don’t throw in an element just to create confusion. It still has to belong in that setting.
I don’t want to imply that every single thing you describe in your entire book has to have deep meaning and plot relevance. The purpose of a Ming vase on a shelf may only be to show the wealth of its owner. You do need to describe your settings. Just keep in mind that the time spent describing a thing should increase in proportion to how important it is to the story. So if the Ming vase is only there to demonstrate wealth, a single phrase will do. But if it’s about to be stolen, or if it’s so precious to the impoverished widow that she refuses to sell it despite her straitened circumstances, then spend more time on it.
The opposite of plant without payoff—pulling a gun we haven’t seen before—can sometimes look like a deus ex machina, although the folks at TV Tropes have a much earthier name for it. So if at the end of your story some critical thing comes into play, whether it’s a weapon, an object, or a skill possessed by one of the characters, it’s best to go back as you edit and plant at least one reference to it early on.