When you realize you're being more productive on working with your WIPs when you're writing/editing them backwards. I've done this before, but it's still surreal as it hasn't really been this extensive. Writing the ending and knowing what you're writing to provides a lot of motivation.
It's still weird for me because a lot of my projects have been pretty straight line sequential. Chapter by chapter, one after the other. I might have to try this more often since I'm writing faster for it. The outlining's helped a lot too.
Happy reading/writing all.