I think the distance you drive per day (or even multiple days) shortens as you get older. There was a time in my life I could drive 24 hours non-stop. (OK, I actually drove 20 hours non-stop a few times when I was much younger).
Now, both my wife and I agree, actual driving times get's maxed out at about 6 hours of (actual) driving.... whatever distance that translates to.
We find ourselves stopping about every hour (or less) for something now, and if we have the grand kids with us, we stop even more than that sometimes.
But the actual driving times turns out to be about 6 hours, and we always try to stop (wherever we're at) around 4:30-5:00 PM.
If we push farther than that, we often stop completely, wherever we're at the next day. We found ourselves exhausted after a hard day push the next day, so we stop.
One thing you really need to get into your head? It's about the "journey" too, not necessarily the "destination." If the journey is "hell" to go through to get there, once you reach the destination, you'll be so ragged out, so tired, and so irritable, so aggravated, you won't be able to enjoy the destination.
If you do not plan on making the "Journey" part of the fun, you've really missed a gigantic concept of what RVing is all about.
I still blow my wife's mind when she sees a road sign that says, "Big Betty's ... shop ... 20 miles ahead" And she points it out to me. 20 miles down the road, we're sitting in "Big Betty's" parking lot. We go inside. We have a wonderful experience that would have been missed if we would have just kept driving. We get ready to pull out of the parking lot, she grabs my hand, and says, "Your Wonderful!"
Now... THAT is the JOURNEY!