Oh. Sorry. I thought Welteam's explanation already covered this, so I just added how I do my app updates. I guess I just made things more confusing.
All apps are installed system-wide on the phone. If you install an app to the phone via one profile, the app is installed system-wide. The only difference is other profiles don't have a "link" to that app.
If I "install" the same app to the phone via two different profiles, there is only one app installed and a "link" to the same app installed is "linked" within the two profiles.
Any time an app is updated from any profile, it updates the app system-wide. That means if User A and User B have the same app, both User A and User B can update the app and that update is applied to both users because they're "linked" to the same app.
In my case, I installed many apps on my phone via my "App Updater" profile, then "installed"/"linked" those same apps in other profiles as needed. When I update apps in the "App Updater" profile, the app is updated system-wide, meaning other profiles with the app "linked"/"installed" will be updated as well.
Hopefully this clears things up.