Is 100 miles on horseback on roads in fall that hard? If I told an experienced marathoner to run 20 miles and it was critical, they'd be done in 3-4 hours and

Is 100 miles on horseback on roads in fall that hard? If I told an experienced marathoner to run 20 miles and it was critical, they'd be done in 3-4 hours and shrug it off. If I told a rando from the street to do that, well they'd look at me like I was insane. I would posit a scout/cavalryman with a good horse with route experience could do that. I guess a horse can do a "trot" at 8-12 mph for 20 miles. That's interesting, it's not substantially better than a marathoner, I have read that humans have advantages over other animals in speed over long distances. https://worldbuilding.stackexchange.com/questions/124606/how-far-can-you-travel-on-horseback-while-pushing-the-horse-to-the-brink https://worldbuilding.stackexchange.com/questions/124606/how... I guess 40 klicks is the general maximum distance by a horse. That's only 25 miles.