The second book in my trilogy is tentatively titled, "Reincarnation." The first draft I came up with was an utter mess, and has a lot to do with why I had to go back and do a fourth draft of book one. I needed a stronger foundation for the later novels, and I'd figured out some parts of my characters as I wrote.
Right now, I'm three handwritten pages into this draft. I am, more or less, starting from scratch. I'm adding a perspective character, tightening the narrative, and letting plot happen in the first 100 (double-spaced) pages instead of letting the characters wander. I'm going to read through the first draft to see if there's anything salvageable, but, mostly, I'm scrapping it.
I've gotten some flak from my writing group for my perennial rewriting, and I've read and heard writing advice that says to stop picking at one book, to move on to the next one. The thing is, this story changes so much from one rewrite to the next, that it feels like a whole other book.
I do agree, in principle, that there comes a time to set the book free to see the public. But I also want this trilogy to survive, to be published, to be read and adored. It can't do that if I just let it go. Just in my rewrites, I've already learned and developed so much as a writer that the first and latest drafts could've been written by different people.
There will come a time when a rewrite would change the story so drastically that I might as well write something else. There will be a moment when I can go a few months, reading other writer's perspectives on the craft, without realizing I'm making a stupid mistake in my trilogy that I need to fix. It will never be perfect, I know, but it's my story, and I get to say when it's done.