The first post on this thread was July 23, 2019 (more than 4 years ago), and there are 5 pages of posts. Yet, this topic is still as relevant today as it was 4 years ago. There are lots of good comments and I read (almost) all of them.
I have come to to some general conclusions, based on ALL of the comments.
1). How long and how far you travel on a daily basis is strictly your own decision. Everyone does it different.
2). As people get older, (as a broad observation), their length and distance of driving per day gets shorter.
3). The length and the duration of the day is also "driven" (pun intended) by the intensity of the need. In other words, when there are hard, fast, and fixed deadlines, EVERYONE, regardless of age or what they are driving, will push themselves longer and farther than their own true "comfort level."
4). When traveling in an automobile, people will push themselves farther, faster, and on more aggressive time lines. Commercial drivers will push themselves up to the max allowed legally. RV drivers will (generally) drive slower, shorter distances per day, and not push to the limits of their endurance.
5). As a (general) observation, the average hourly speed for RV driving seems to be 50 mph when factoring in site seeing, fuel stops, and rest stops.
6). As a general observation, when folks push the driving schedule to it's max and push themselves to the max, upon reaching their destination, they are usually so tired they CAN'T truly enjoy that destination. Depending on how old they are, they need everything from a day to several days of rest before they feel "human" again.
In the end, it's everyone's comfort level that "drives" them.