They had warmish weather and a tailwind, I think. From the little that got out about the nuts and bolts of the trip, I think they were a bit concerned on leaving Flagstaff, but with conservative driving were able to relax toward the end of the leg as it became clear Blanding was in range. EV Trip Planner suggests that with a 0.9 speed factor and 40 degree temps, the route will require about 252 Rated miles.
By the way, I'm contemplating a trip through that stretch the last week of February, and I found an open-all-year RV park in Tuba City that could provide a 50A booster charge to make Blanding-Flagstaff less dicey, especially westbound.
Ya, they didn't drive like normal people. I forgot where I saw this information but supposedly they didn't drive with the heat on. They were given handwarmers at superchargers from the support van. It might have been an unpleasant trip with all the extras turned off, but they still made it.