It's up to each individual to decide how important their data is, how many backups to keep, and where to store them. The internet police won't arrest you if you have no backups at all, but if you come here complaining that your data is lost and you have no backups, some of us will laugh at, not with, you. Backups kept at the same location as the main data drive may be safe, but that's not enough for me. I'm just one rando on the interwebz, though, so manage your strategies as you see fit. You being anyone who happens to read this.

