Some observations about scenes, collected from reading too many short stories and marking up too many drafts:
The first sentence of a scene is doing more work than you think. It sets the clock. It tells the reader where they are in time, in space, in emotional register. Get that sentence wrong and the reader spends the next paragraph orienting themselves instead of inhabiting the story.
Alice Munro can cover twenty years in a single paragraph and then spend three pages on one dinner conversation. The ratio tells you what matters. She's not summarizing because she's lazy. She's compressing time so that when she finally slows down, the deceleration itself becomes a signal: pay attention, this is the scene that counts.
Most scenes go on about two paragraphs too long. The impulse to explain what just happened, to make sure the reader got it, is almost always the impulse to not trust your reader. Cut the last paragraph of your scene. Read it again. Nine times out of ten, the scene got better.
Denis Johnson's narrator in "Emergency" from Jesus' Son doesn't understand half of what's happening around him. He's high, or coming down, or dissociating, and the scene works because his confusion is specific rather than vague. He notices the baby rabbits, he notices the hitchhiker, but he doesn't connect them to anything meaningful, and that refusal to interpret is what makes the reader interpret everything.
A scene ending is stronger when it raises a question than when it answers one.
Chekhov's advice was to remove the first and last paragraphs of every story. I've tried it on individual scenes and it works there too, maybe even better. The instinct to warm up at the beginning and sum up at the end is the same instinct, and it's almost always wrong.
The worst thing you can do in a scene is have two characters agree with each other for more than a sentence. Agreement is the end of tension. Even if your characters are allies, even if they love each other, something in the scene needs to pull in a different direction or the reader's attention will wander to whatever's in the next room.
George Saunders cuts to black like a filmmaker. His scenes end one beat before the character processes what just happened, and that missing beat is where the reader's own emotional response floods in. He trusts the gap. Most writers fill it.