[MayflowerMadam]

“I use a simple and copious USB stick between computers, and make interim back-up files on each,”

I kind of do that now. My USB literally has the label “sneaker net”.

I back up my main PC regularly. It’s a good idea, except my older external drive died so I lost those backups. The cloud keeps calling me, and I keep ignoring it.

[Worldtraveler once upon a time]

Good on you. I erred in not being more detailed. Because we too have enjoyed the "crash" from time to time, I backup onto to separate, stand alone HDs on a that "regular" basis. If we lose one, there remains one of two.

As to servers and "cloud" stuff, they too suffer the occasional crash. Read the EULAs close enough, and they accept precious little responsibility of your to-you precious files. Our precious files and their duplicates are right here, at my desk. My cloud....

All best.