So this just reminded me of something I noticed about my favorite route to cover.
There are some routes in my center where the system (ORION or something similiar, idk) has the wrong speed limits inputted for the roads in the area. So the system thinks it'll take you 12min going 25mph, but the speed limits actually 40mph and you get there in nearly half the estimated time.
That might not make much sense, but the way it works out is that you go the speed limit and steadily watch your estimated arrival time go down, down, down. Makes me feel like I'm haulin' ass and the volume just melts away off of the truck.