My current backup approach uses Syncthing, but only to replicate all data to a single point, which is then backed up properly.
All mobile devices sync to home, that box is the authoritative data source for everything: mobile devices, user data, media files, etc.
It replicates to two other local data stores (this for quick recovery should a drive/device fail) and is backed up to a cloud service (should I have a catastrophic event).
Its not a perfect 3-2-1 setup, but addresses my risks well enough.




I agree with everything except the offsite, offline, external drive.
In my experience, cold drives fail more often than live drives, and you get no warning when this happens.
Drives weren’t engineered to be offline but to be powered on continuously. Things like lubricants in the spindle, but especially the read heads pivot were designed around this. How anybody us have heard the click of death - that’s the read head having issues moving.
Plus external drives have heat dissipation problems. They’re good for short, intermittent reads, but when initially copying data to them they can get quite hot. I regularly recover and rebuild drives for family and friends and have registered these things at 120° F+, so I keep an old case fan on them during recovery.