Oh, that's really interesting! I can't leave sentences unfinished like that generally because it will bug me too much, but placeholder scenes or sometimes paragraphs, I do. So I'll have something like 1100 words of a scene and then

[something? family dinner? show the connections between them, make them live]


Rarely in the middle of a paragraph I'll leave notes to myself: [is this how gaining access to a federal building works? Check with (name of a friend who'd know)]