Still no news from the producers, but I think the lawyers are busy...
I've been doing rewrites lately on two scripts. I'll typically work one month taking a screenplay from concept through outline and to first full draft. Subsequent rewrites then take another two months. So, before I even show it to potential purchasers two-thirds of the work was in rewriting.
I imagine for others it might be different. I go through first drafts quickly, just writing past areas that feel clunky knowing that I'll go back and toss it out in a re-write. More exacting people might take longer on first draft but need fewer rewrites.
One of my screenplays is a noirish thing and I wound up having a bunch of back story in it to prop up the plot. That was nagging at me for a while, which is one of the reasons you put things away for a bit -- so that they can nag at you enough that you actually change them. And do change them -- that nagging is your instinct giving you great advice.
In a movie you really can't afford much backstory; there's just not enough space to give it an adequate treatment. That meant I needed to dump almost all the backstory -- and that meant scrapping large, honking chunks of the text. One good thing about that is it cultivates a feeling of detachment -- you've already killed so many pages that killing some more doesn't feel so bad -- and that's good to have when you get around to working with producers and directors.
Given the breadth of the changes I started to wonder whether it would be just as easy to simply write a wholly different screenplay. Certainly my gut instinct is "no" -- but I'd like to have a richer justification than gut instinct.
There's the "not wanting to feel like a quitter" justification. You know, finish what you start; see it through to the end, and so on. But that sounds as tautological as gut instinct.
However, there is something a rewrite retains, even when you throw away every word and start writing again from the beginning. You have a picture of the overall structure -- what worked before and what didn't, what the timing should look like, and so on. Also, a bunch of the characters have been given idenitities that one can hang dialogue and motivations on, or make distinct with a few tweaks.
I think that's why the WGA gives so much priority to the first writer -- note though that there's some debate over whether the WGA gives too much priority to the first writer.