We do 330 miles or stop at 3:30 which ever comes first. We make reservations for our final destination, before we leave. Other then that we do like everyone else call after lunch because we will know by then were we are stopping for the night. Never have issues. If you want to stay at a national park I would make reservations ahead of time. We were just at Zion and 300 camping spaces in the park were 100% booked for the 6 days we were there. We stay at a park in town as we like it better then being in the park without electricity.