Things like the commercial break.
Okay, that's not what it's actually called - I call it that not only because I have no idea what term is appropriately applied to it, but because that's what the thing feels like. I'll be reading through a story, generally be in the middle of a conversation between two people, when the author will toss this my way:
That, in standard manuscript format, indicates a line break, and line breaks are generally used to separate scenes. What really gets me, what really grinds my gears and so on, is when it feels like that line break is misused - when it's jammed in the middle of a conversation for absolutely no reason. I was always of the impression that a scene should end on a conflict, an unresolved question, or a potential sticky situation in order to encourage the reader to keep going on. What I tend to find more often in these twentieth-century stories are line breaks inserted seemingly for the sake of line breaks. There's no scene transition - when they're misused, things pick up after the break exactly where they left off, and it's not even a natural break.
Let me illustrate what I'm talking about - here are a couple of paragraphs from my short story The Platinum Desolation, very slightly modified to accord with what I'm complaining about.
"Then it's a betfair that Lady Luna didn't start potshotting their ride until they were long after gone," Sujatmi said, ensconced in their own rumbling rover. "Question is, why haven't they come back? No one's filed any recent missing reports. The rover's listed as surplus out of Yutu, thirty years old. They rent them out to tourists, I've heard."
"Goddamn idiot earthworms," Christine stood and sighed. It figured she'd have been led there when the beacon needed quick fixing, lest some hauler wander off the trail and end up paying an unscheduled visit to Neil Armstrong's grave. "Don't know the first thing about their own security. They'd take off their own helmets on the surface if they could."
That break seems a bit out of place, doesn't it? I mean, nothing's changed. The situation is exactly the same as it was before, the characters are doing the same thing, and the break feels as artificial as a shoehorned TV commercial break. There's no reason for it to be there.
Maybe this was some kind of style back in the day. I don't know. All I know is that it's distracting; the way I see it, scenes should be separated because they're different scenes, not because separate scenes are just something that's done.