I’ve rewritten three books now.
The one I did the biggest rewrite on was a 90k(approx) book that I was never happy with when I wrote it. The ending was awful, the character’s didnt feel real enough. I still let the book settle in my head for a good 6 months before I touched it. But I spent 2/3 months last summer rewriting the whole book. It’s now like 120k and I feel so much better about it. It needs a little more work, just fine tuning and a few extensions and deletions of some stuff, but not enough to be a rewrite if you see what I mean. That will be it’s 3rd draft.
The other book I rewrote is being trad published this year. It started as a first draft, then got rewrote once to change the POVs (it’s a dual pov romance book), and a lot of the plot got changed so it wasn’t a major rewrite but things changed, moved, character got fleshed out.
Then a year later, I rewrote it again. Not as big, but chapters added, povs fine tuned, flashbacks added, chapters added and just an overall overhaul. No plot changed though. That was it’s 3rd draft, but 5th edit overall when you incorporate little grammatical changes.
The publisher has just received the manuscript back from the editor, and I dont know what they’ve changed yet, so I can’t tell you if they’ve rewrote it or just fine tuned it, but it’ll be its 6th edit - 1 of them being professionally done.
My most recent one was a book I only wrote in October - January (with a month break in between for NaNo) and I needed to rework some of the plot, change some of the characterisation so it involved a lot of rewriting scenes and reactions. It wasn’t a major thing, but it lengthened the book quite a lot, and changed the plot enough for me to consider it a rewrite. I’d say one rewrite for that is enough as I feel really satisfied with the book/plot now. It needs another fine tune at some point, but not a rewrite.
Overall, I’d say generally, I tend to consider a rewrite as changing some plot lines or adding chapters and POVs etc. I wouldn’t tell you how many is too many, but I think I would say it would be when the book doesn’t feel like it should to the author.
I personally will always rewrite until I am satisfied with the book as a whole. That is ignoring little things like grammar or the odd thing like add description here kind of editing. When the plot as a whole to me, feels complete, I’d say that is enough rewrites. If that mean I have to rewrite the book 5 or 10 times (I’ve never done that much yet but you know example lol) then thats what it takes.
Luckily, I’ve never felt compelled to really rewrite something too many times. And those 3 books that I have done have only needed a few at best. I’d say just keep going until it feels right to you.