Re: Upgrade ? No..
I've always created a new partition and installed the new version
Same here but always run multi-boot on my main laptop. By starting with a multi-boot system there's no need to 'create' any new partitions when you want to upgrade. Pick the OS partition you've decided to upgrade, delete it, install new OS, paste in (large) apt command to reinstall required packages - go for coffee. If you don't like the result boot one of your other partitions that you have maintained.
Obvious disadvantage is maintaining patch levels on multiple OS partitions.
In the unlikely event that the new OS damages your /home partition, restore from backup/snapshot/Nextcloud whatever.
The only time this has failed me was when the very rarely booted Windows OS self-updated (thanks) and stamped all over my partition table - took nearly half a day of fiddling before I gave up and swapped the disk to start again.