Only during the day and only when the youngest was under two. During those years, we'd drive a lot at night and then we drove until the baby woke up or the car needed gas, whichever came first. Once we all were over the age of two, the average time between stops rose over 4 hours, closer to 5 most of the time. I think our record, though, was about 6.5 hours in a middle-of-the-night leg when my dad joined a convoy of semis and just drafted behind them for hours.
It was a requirement that everyone use the facilities every time we stopped for gas even if you didn't think you had to, and if you needed to stop later and you were the only one...it could be quite an adventure getting in and out of the vehicle after it was packed and between that and the time wasted on an extra stop, let's just say you were not very popular. There was a lot of peer pressure to learn how to hold it.