In my early 20s, I drove from Austin to LA in about 24 hours, then up to Vancouver. Got to destination, checked in hotel, spent 2-3 days asleep before I could. I took it slow (five days via a different route) when going back home.
I won't do that again unless there was an emergency and I couldn't get a flight.
If I were driving a motorhome that took effort to keep on the road due to passing 18-wheelers, side winds, and additional fatiguing effects, I wouldn't even think of anything more than 300-500 miles. When I get near eight hours on the road, I'm going to be pulling over and using an app to hunt for and reserve a spot at a decent CG or RV park.