Subliminal
Only one user:
- main profile with my daily life, everything FOSS with no GPS (Google Play Services)
- private space with some apps that require GPS (like bank, gov ID), I tried not unlocking this for some days and basically I can leave without it for most of the time.
- work profile with some apps that I need for... well, work lol
Sometimes I create a second user just to test some applications, to make sure they don't have broader access to something on the smartphone, but after tests are concluded, user is deleted.
Usually these are apps I do not trust yet and reading around I still don't have the full picture of them.
While some things can be justified by personal preferences, on a logic base most of the apps do not need a second user, especially after the advent of private space.
If a specific app is known to be intrusive, you might ground it on a different profile/user, but most of the heavy lift is already done by the permission system.
For example, if you install WhatsApp in whatever profile, there will be some information always available (like the list of installed apps in the same profile) and all the rest is managed by your permissions set.
If you do not give access to the storage, or you implement a storage scope, whatsapp will not be able to look at your data anyway.
Segmentation by profiles is useful mostly against rogue apps or some attacks.
Having 47 users (with 47 contact lists and 47 different storages and so on) is almost never more effective than using contacts scope or storage scope.
You can appreciate some differences when 2 apps start to talk each other, like when an app that need GPS or 2 apps share the same account or 2 apps use IPC to communicate.
An example of an app having different behaviour with/without GPS is Signal: it will use GPS if available or fallback to its polling if not.
An example of 2 apps sharing the same account is GPS + Google Maps: maps will auto-login at first launch.
I currently do not have any meaningful example for IPC, but it's still a possibility.
In this forum (and in this thread) I read more than once of people using the main profile of the owner user just to install apps and nothing else, but honestly I still fail to understand how this grants more security or more privacy.
Special mentions about different profiles can go to having the same app installed more than once and the need to have two apps entering different VPNs.
These needs are actually solved by having a new profile.