Ya, from my conversations with authors not often, but an author will often pay out of contracts. But, if you are on book 3 of a well-selling series at Tor I bet you do (I don't know just guessing).
Did you get any help from an editor or was that out of pocket?
I didn't need--or at least didn't think I needed--any serious outside structural editing. They did do "developmental" (but minor) and copyediting. I write a lot and knew the topic pretty well. I had work colleagues read over for tech review as appropriate. I have been paid out a little above advance but we're talking very small numbers for someone on a decent tech salary. The benefit was 90% reputational.
Did you get any help from an editor or was that out of pocket?