Your approach is correct and it makes total sense.
The biggest blocker is that there’s no way to tell good!reddit from bad!reddit
The interesting question is why do we want to reduce screen time, what’s the goal here and what will the side effects be. In my opinion, it’s just important to decrease the usage when it is a parasite on quality time slots (for focused work, for family). I put the longer explanation and solution idea in the post below.