For me it depends on the vehicle. When I was driving trucks, my company capped us at 10 on/10 off. I could usually get about 600 miles in that time, mostly highway miles.

On my motorcycle, I tend to do 300-400 a day, the RV is about the same. If I'm in a car I'll do 700-800 easily. I've driven from Los Angeles to Seattle in a car in two days.

Of course it I'm stopping to see anything at all, expect these distances to be halved.