If itâ(TM)s life critical, more than one.
Personally, life critical stuff gets put on a home Synology, backed up to Backblaze B2 (From Synology) and mirrored (with Resilio) to my office and then separately encrypted and copied up to Dropbox (with Hyper Backup). So at any given time, Iâ(TM)ve got like 3-4 copies of data. Computer catches fire/stolen. Iâ(TM)m good. House burns down. Iâ(TM)m good. Earthquake takes out PNW, still good.
Less critical stuff, I just mirror off site. Sure, would suck to lose part/all of my plex library, but it wonâ(TM)t kill me.