Sometimes, being anal is a blessing--but when it comes to knowing when a piece of work is finished, it's a definite curse.
Change a word here. And a word there. And there. Then change one back. Delete a sentence, then paste it back in. Tinker with paragraph order. Monkey with the leading. I could do it all day long, and it would likely drive me slowly insane.
So I force myself to stop, in spite of that little voice in my head that tells me one more change is going to make it SO much better. It's hard to do sometimes, but it's absolutely necessary--not only for my sanity, but also in order to meet deadlines.
I'm sure I'm not the only writer who doesn't know when to stop . . . so how do you deal with it?