I know I'm late to the party here, (ran across this post while looking for something else) but I thought I'd add this use case as a response...

on my app's user preferences screen, I show a dialog and call requestPermissions when the user enables the bluetooth features.

I use checkSelfPermissions to verify the permissions are still granted before the bluetooth scans since the user could enable the feature in userPreferences, but then revoke the permission from the system's appInfo screen. If I didn't do this, the app would crash since the preference option said to run them but the app permissions are denied