When It's Done, It's Done
I get a lot of emails from feedback and consultation services. If you're a screenwriter more than two years, you will be on every junk mail list there is. They all offer to help make your script better. I don't know how many times I've heard a script guru say you must rewrite, rewrite, rewrite. Who says there has to be something wrong with your script?
Yes, you can make a screenplay better with additional drafts. But you can also suck the life out of it. How many of you have seen a Hollywood movie in the past year that just fell flat? Maybe it had a great concept but it just didn't deliver. The reason is too many chefs in the kitchen. There is rarely a script that doesn't get at least one polish by a second writer. Many times there are more like four or five writers on a single project. Each one took their crack and what you're seeing is an attempt by the last writer to make it work.
These days, the movies that receive acclaim and launch careers are developed by one writer with a single vision. Maybe that writer is also the director, but it's one voice. Yeah, maybe it took him/her a long time to raise the money to make their film because every executive said it needed a rewrite. But now that it's a movie, those same executives will kiss that writer/director's ass to work with him. It doesn't even have to be a financially successful film and that guy might be handed a franchise to write or direct.
So scripts are really like a painting. You wouldn't tell the great artists that they left something off their canvas. Or they need one more brush stroke over here. Picasso said it was finished, so it was. If you let everyone convince you that something is wrong with your script, then you will be rewriting until the day you die.
It has to be your gut feeling. You get to decide. When it's done, it's done. Now stop writing and go knock on doors.