I have like a million drafts of everything. The original handwritten draft, of course, exists in its own book. Once I type that into the computer, it gets saved as my first draft. Every set of edits is saved afterwards to my harddrive under a different name, like “OWTSAS-Draft 1.” (I keep my digital drafts in other places, too–besides my main harddrive, I keep copies on my flash drive and a separate external harddrive.)
Why do this? Easy: I might need to Frankenstein something.
Sometimes I’ll be five drafts in and realize, “Hey, I wrote a great sentence for this back in draft one!”
Thanks to the miracle of backing up my older drafts, all I have to do is open the old draft, extract the phrase I want, and paste it into the current draft I’m working on. Some work later, I’ve created the perfect paragraph! I call this practice of piecing together parts of different drafts “Frankensteining”, for obvious reasons.
I used this practice often when writing papers in school, and it’s also come in useful in writing Out Where the Sun Always Shines (which wound up having five digital drafts total).
In computing terms, text takes up very little space, so backing up every draft isn’t a big deal, even with a huge novel!
A backup is like a spare tire, easily forgotten when not needed, but when you do need it you really do need it.
— Unknown (taken from Backup.info)