The huge benefit of using the oAuth 2.0 Authorization Feature of Postman is to switch between multiple sessions via the “Manage Token” dropdown without having to re-login. Also you can make use of the “auto-refreh token” feature that way. By switching between sessions the “tests” tab is not executed.
When setting up a manual authorization request you loose the benefit described above.
So thanks for the hint, but this does not help me that concern.