Bear was watching another counter-tracking video because they had to escape bandits. They made it two hours before Bear rolled critical fail and made them even slower.
Oh, I forgot to mention that any travel beyond 12 hours a day also follows this rule. You risk exhaustion.
Now that said, exhaustion isn't that bad. It has a blanket -2 proficiency on everything affected by proficiency, AC is not affected, and since until higher levels, you only get +2 proficiency anyway, higher levels of exhaustion only affect speed. So even having exhaustion 2 won't stop you from traveling.
I am also allowing concurrent recovery for exhaustion so if you have exhaustion 3, 4 whatever, you can get rid of all levels on long rest, specifically sleep. For now this seems broken but it's very unlikely to get exhaustion 2 except by critical hits and as a front liner, Bear's had exhaustion 2 after a battle and requiring 16 hours of rest after an encounter seems pointlessly harsh.