There would be no noticeable loss of time as normally we have the auto-save feature on, but imagine an app tha has 10 of 20 subs, you tned to go by stages and do specific event driven subs before any "calculations" subs, at least I do....So if after all the event sub were done if you had an error in a "calculations" sub that you just couldn't see", a backup file would be of interest in order to restart Exactly from where you were, and re-think the troubling sub...
I've had ocasions when it was easier to me to just restart the hole project because I just didn't know anymore what subs worked and were could be my eror...If only I had Backed up that time....Of course we can alway do our own back-up before re-opening a sbp file, if we remember to...