It’s hard to get a good sense of it since you can’t exclude apps. I don’t actually use Screen Time because of that.

My gym app is on the screen for an hour but I’m only looking at it and interacting with it for a few seconds between sets.

Maps is on whenever I’m in the car.

My timer app stays on screen while the timer is running unless I manually lock it.

I leave my phone on the kitchen counter with the Music app on screen all the time.

For the real time wasters like Reddit, Twitter, Instagram, I’d say 2-3 hours on a day where I have other stuff to do and more than that on a day like today where I laid around on the couch most of the day.