Deadlines do work. However, since I've got to meet loads of them at work (and, much worse, have to remind others of their deadlines, a task which often involves a lot of ass-kicking and knife-to-the-throat-situations over the phone) I try to avoid them at all costs when writing my own stories/books.
But usually I don't have much of a problem with "letting go". I'm aware that everything I write could be written differently, certainly better, too, but there's just that much editing and revising I'm willing to do. Most of the times I just want it to be finished because I've got another couple dozens of ideas to write about.

Life's plenty long enough to drink the odd bottle of bad wine, but not long enough to write everything in my head. So I better hurry hp