The problem with being a writer is that you're never off duty. Ideas arise, phrases occur, characters appear, and they have to be captured before they fade in memory.
A subdivision of that is the editing process, which can stretch into infinity. I have a very nice editor who made some very helpful suggestions on a manuscript, and I've been working on them. So am I done? Did I do what she asked me to? Yeah. I mean, I think so. But when someone asks for more setting or more clues to character, (to quote George Michael) how much is enough?