I'm using my MacBook as sort of a "satellite" to my main iMac. Anything of any importance on the MacBook is synced via iCloud over to the iMac, where it gets backed up to a Time Machine drive daily and an offsite drive monthly. Important to note, the iMac has iCloud Drive not set to Optimize Storage, so it downloads everything -- that means I have to maintain a lot of storage, but it's worth it to know I have every file I own fully downloaded and backed up.
I back up the MacBook every week or two just to make it easier to restore a new one if it gets lost or broken, but at any given point in time I've got all the important stuff covered.
I suppose one *could* just stuff a Mac Mini into a closet somewhere to replicate something like this, but probably not the most efficient use of resources.