I'm eight or nine scenes ahead of where I scheduled myself to be, so I feel comfortable taking a short mental break from the editing to write the new scene in Chapter 4. So far I've only added paragraphs here and there, but this one is a complete rewrite of a scene I wrote during NaNoWriMo.
That's the highlight of doing multiple drafts, though. You force a scene during the first draft to get to where you need to go, and then the second draft is for cutting and replacing with something that flows and is cohesive to the overall storyline.
For the record, all of that can be exhausting -- but! the benefits of the editing outweigh the temporary discomfort. When they said editing can be painful, they weren't kidding.