Back in the day – hey kid, pour me a whisky! – when we had to walk two miles to the café to find the Internet and a good mocha, the "new" OS was not necessarily "better." Sometimes THAT APP YOU MUST USE had not been updated. Or that bug was not found by the Code Monkeys – "Really, just go into Terminal and type this long code and hope you do not mix up 'l' with 'I.'"
Or your current computer is not compatible with the Latest and Greatest.
Back then – through sleet, driving hurricane, and 100℉ in the shade – sometimes it was best to wait a few iterations when a new major upgrade came out.
I have found that less of a problem. Still, I would generally make a bootable clone, then try out the "new" update, see if everything works. If it does not, it was just a matter of booting to the clone and fixing. The Kids These Days – with their hot rods, bobby socks, and "the B-Bop" – use Time Machine.
Now get off my lawn!
– J.D.