Absolutely agree. You'd think most people would, but I know a lot who don't. Apologies for stating the obvious.
Personally, I use a Mac which is backed up hourly to both cloud and external drive hourly in addition to three external drives, one being a back up of the other two in case of a drive failure. The external drives are only connected for the backups and then disconnected again. Feel free to call me paranoid, but I think I'm covered :-)
