I've printed my futuristic (67000 words) and am working my way back through the story to tighten and proof. Every pass of a manuscript shows you something else about the work and that's where I am at the moment. I thought my first three chapters were done, but out of the blue I had some feedback that has thrown me into a spin.
So back to the drawing board I go. Changing something so early in the book has implications right through to the last chapter. The book I thought was nearly done is now undergoing another major revision. Wish me luck.