I like this topic, except I forget what squirrels are. We built a house in a new development that was once a meadow, so trees were pretty sparse before the builder got to it. We actually do have a grove of trees, but I think the poor squirrels were so traumatized by whatever clearing the builder did that they've left and not come back yet.
Which is a nice segue into my response about organization. If I didn't have my meticulously dated files, I'd be like those squirrels - hey, you took what I knew and made it unrecognizable!
I tend to edit as I go along, but once I get to THE END, I save that copy with the date (always written as a 6-digit number: 100906 = October 9, 2006). Then, when I start to edit, I save the next version as whatever date I'm working on it on (ooh, not good sentence structure! But that's why we write fiction - we can do fragments and dangling participles and slang and call it "voice" ). That way, I know what's the most recent version. When a few months have passed, I'll take a group of old dates and stick them in a file folder and call it "older versions". Once I'm pleased with it, I take all the older versions off the laptop and put them onto a disk - just in case an editor suggests changes (hey, I can hope!) that I had at one point.
An agent in NJ made a comment like that: someone asked her how 'hands on' she is with edits and she freely admitted she doesn't have editing experience. The one time she suggested that an author client make the heroine a little older, and the author did the edits, the editor who bought it wanted the heroine a bit younger. I hope that author saved her earlier version :)
You know, if those squirrels buried their nuts in date order, they might be able to find the suckers and JL wouldn't have to pull up baby oak trees in the spring.
Of course, she could always mail them to me. :) -Judi