It’s been a fascinating progression.
– Unsold Early YA novel: Kept 2/3 of my first draft.
– Bones of Faerie: Kept about 1/3 of my first draft. (To around the point where Matthew finds Liza in the woods.)
– Thief Eyes: Kept the prologue.
– Faerie Winter: Kept … nothing. Wrote the wrong book, in the wrong town, with the wrong characters, en route to finding the right ones. (This was also, maybe not-coincidentally, the book where I decided to fully embrace my process, and stop worry I ought to be fighting it.)
– Faerie After: Kept bits and pieces throughout. Wrote something closer to the general neighborhood of the right book. Sort of.
– New Book: The structure has a chance of being more or less right again, even if all that happens within it gets rewritten. At least for the 2/3 already on the page–last 1/3 is still impossible to predict.
Where saying I kept something means, I kept the basic story, but not necessarily much of the prose. And where large amounts of what on paper went unused or changed utterly actually informed the magic, issues, and themes of the larger book. Which is why I don’t think of any of it as time wasted or mistakes made or things thrown away, but all part of a larger process.
And then there was Secret of the Three Treasures, where I pretty much kept the original book and my edits were mostly surface edits, at least compared to my usual process. Because sometimes, a book comes along that’s just a gift, and you can’t (I can’t) plan on it and can’t predict when that will happen. I’ve had at least one short story like this, too.