When switching from working in one world to another, I've found the transition is easier when I edit the previous chapters of next project before I begin writing. Therefore, having the last third of my historical co-write's revisions as tonight's activity was perfect timing (it also feeds into the feet-dragging that occurs when I'm writing the last chapter, as if slowing down will somehow prevent the inevitable end of this story).
There are a few notes I made as I was reading, things that need to be verified to ensure I've stamped out any inconsistencies, and after I completed the revisions, I spent the rest of the night cycling backward searching for things like... the evidence couldn't portray the hooded man participating in the torture of Catherine Ellis because of his location at the time.
That particular example actually didn't need to be corrected, nor did most of my list, but, like that thought you get when leaving the house that reminds to you to check for the fiftieth time that you have turned off the stove, I'd rather catch it now, than after publication.
Tomorrow I begin the final chapter of the first book in my historical co-write, and I'm finding myself sinking into the melancholy which accompanies that admission of another completion.