You all do know if we're hit by an electromagnetic pulse everything is gone.
Except what you printed out or had published, on paper.
An EMP from a conventional source (nuclear explosion, etc) would only likely have measurable effects over a small, local region. Which makes internet-based backups very valuable. Anything producing EMP effects over the entire planet is going to give us much more to worry about than whether or not our drafts and character profiles still exist haha
Regarding general backups, I'd take advantage of whatever cloud or dropbox-style service you can find and that you like the functioning of. Every cloud service is going to work slightly differently, and obviously you don't want it to overwrite things in weird ways as described in the OP.
Whatever you do and whatever your self-written rules for backing up, you should always have an off-site backup location. Keeping an external hard-drive under your bed and another one in the linen closet is a great system; until the house burns down or you get robbed. It's very much not likely to ever happen, but uploading to a web server is a tiny amount of effort for a whole lot of redundancy.