There's no good guideline - if you want a local cache that transports across user migration, that's the show. Windows doesn't really have a "separate your local disk cache from your backups" method, but you can certainly do the Cleanup Task to remove some things that buy into that modal that's 25 years old :)
Let's just call it what it is: a complete mess. Some apps install their binaries in there, some just config files, some all your data.
If there are guidelines (and they are not conflicting) about 1/3 of apps are ignoring them.
Also good luck trying to back it up with robocopy or anything, maybe windows' own backup tool can read it while running on that account, I usually get errors, which I think are mostly fine to ignore.