Mostly, I've decided that if I ponder it too long, I have to leave it as is. The typesetter people will be grateful, I hope.
I'm making a lot fewer changes than I did on my Author Alterations for The Duchess etc. A couple of times I've changed words so I wouldn't use the same distinctive word in too close proximity (well, a few pages proximity). Otherwise...only four small errors so far that I've seen, one of those a capitalization thing that would have been okay even if I hadn't noticed it. I'm into the second hundred pages now, of 381.