Not everyone uses Time Machine, though.
of course, but I was thinking that Harv probably did.
Nope. Harv does not use Time Machine. He has 3 internal and 7 external volumes on which he keeps bootable backups so that he has a myriad of backups of various vintage-- from 6 hours to 14 days old. Also, critical data is encrypted and stored on Dropbox, and on two other (old) computers.
He is not opposed to Time Machine, just never saw a need for it.
Other than moving my wife's Mail Download Folder to a thumb drive, I see no viable alternative(s). <sigh>