I always heard that it was 1 day off for every 10 miles ridden. A week off for riding only miles seems excessive.
But if that is the case, what do people do who ride multidays. I think the down time depends on the rider (I sometimes don't want to get on my horse for a week after a ride). Depends on the condition of the horse. Depends on if the horse finished the ride with any problems or not. ie - lameness, dehydration, colic, etc..... May even depend on the over all attitude of the horse. After a ride when I turn my mare out to pasture I pay attention to how she leaves the corral. First few days she may just walk out, then may pick up to a trot, then will fly out at a gallop. I figure when I see that she is rested and ready to go again. Just like everything else involving horses. Depends on..............many things.