I can't believe I'm actually able to say this for once, but you are incorrect.
I just updated my tablet using odin, and kept root, and didn't have to reinstall anything, all my apps, all my setting all still there.
See, what you do, you follow the steps from @PewPewK post back on page two, using magisk manager to patch the ap file.
But and this is pretty much the only difference, when you flash everything with Odin, you use the HOME_CSC file instead of the CSC file.
Only thing is all system apps are back, so if you uninstalled or disabled any of them you'll have to do so again, but hey, that's a lot easier then reinstalling everything each month.
Excellent work. I wasn't provided the option to update my security options so it looks like I missed something on my end