I do - we used to not have real highways 10-20 years ago. And the main issue with not overtaking a car-truck that is going just 60 (in your case) is that sooner or later they will encounter someone going 40-50, and they may not be able to overtake. And because of that uou end up driving 40mph on a 70mph road for hours.
Between all the vehicles I've driven in my life I've accrued, got I hate that I know this number off the top of my head, around 350k miles.
So yeah, I do have experience with such roads.
Then you have no idea what the rest of us are talking about. Western roads are huge, and travel times are long. When you're driving the ~1000 miles between Denver and Los Angeles, 10 mph difference in speed can make your trip up to 2 hours longer. That's not insignificant, especially if you're trying to do it in a single day.
Also, you did not read my post. I specifically said that over the course of those long miles 10mph will cost you 2-3 hours. I literally said that in my post.
You also missed the part where I suggested that no one should be driving for 21 hours, let alone 18.
Let me be clear, trying to drive 1000miles in one day is unsafe.
500+500 with two drivers.