When on a critical path, add your own safety margin
I know we're in stable door territory here, but I have a lovely shiny new bolt for you...
I try to rename the file to a physically new file name at least once a day. It gives me a shovel-load of versions but I can only lose one day's work.
I'm Paranoid, so I also back-up to the server and to a portable memory stick.
If I lose a client's work, I'm that many days down, behind schedule, and liable to having my pants sued off for losing HIS time too! So I have a reason for my paranoia.
it wouldn't hurt to be a bit less trusting yourself...