A well-constructed one-shot reminds me of a chess problem—the entire board is set, but the solution is found in a handful of elegant, necessary moves. The writer must choose a narrative moment that's already pressurized, where the backstory is implied by the present tension. Katherine Mansfield's 'The Garden Party' comes to mind; it drops you into a single afternoon, but the class distinctions and Laura's awakening are all there in the juxtaposition of the party's preparations and the neighbor's death. The plot isn't a sprawling saga but a precise incision. Everything extraneous is omitted, leaving only the essential emotional arc. The reader's imagination fills the margins with what 'must have' happened before and what might happen after, completing the circuit. The skill lies in making those margins feel full, not empty.
It's a different kind of satisfaction than a novel. You don't get the slow meander, but you get a crystallized idea, a feeling captured in a vial. The brevity forces a focus on language, on the weight of a single image or line of dialogue. A weak line in a novel can be absorbed; in a one-shot, it can shatter the whole illusion. That pressure creates a certain intensity you don't always find in longer works, where the writer has room to recover from a misstep.