When on a road trip you should aim to stop every 1 hour to 1 hour and 30 minutes if possible to allow yourself and your kids if you have any to stretch yours and theirs legs and get out and walk around.
I always stop on road trips every 1 hour for at least 10 to 15 minutes for a restroom break and to stretch my legs and to stop my butt from hurting.
If I sit down in the car for longer than an hour my butt usually begins to hurt and go numb so I like to get out of the car every 1 hour to stretch my leg and make my butt feel better.
It also gives me the chance to use the restroom to keep my bladder from becoming too full where I do not have to pee and hold it in.
But you should take 10 to 15 minute breaks on the road trip every 1 hour to 2 hours and do not drive longer than 2 hours at a time so that you don't get fatigued or have your leg cramp up either.
If you have kids then you need to allow them out to pee and poop and allow the kids to run around to keep from getting restless in the car.
If you have dogs you'll need to stop every 2 hours or sooner to allow them to pee as well and to allow them to walk around.