When driving hundreds of miles in a day or just driving hundreds of miles you need to stop every 1 hour to 2 hours to take a break.
Do not drive longer than 2 hours at a time without stopping to take a break and walk around as you can get driver fatigue.
Your legs and feet can also become numb when driving long distances as well.
Sometimes I will drive for 2 hours and then sometimes I will drive for only 1 hour and sometimes for only 30 minutes and then take a break.
Whenever I see a gas station and my gas gauge on my vehicle gets to 1/2 tank then I go ahead and fill it back up so that I don't have to worry about running out of gas.
On some roads there can be 100 miles or even more between gas stations if you're driving on more rural roads.
On the interstate there are usually plenty of gas stations.
Also it's safe to only drive around 8 to 10 hours in a day which means you may be able to drive 500 to 800 miles in one day.