I always assume that the trip home will take less time than the trip out. Even if I travel a loop, they seem to know when we are past the middle. Just so they don't break out of the gait that I ask for, I don't worry about it. I try really hard to get my horse to walk back home on a loose rein. I would have to ask for her to slow down 20 times than to keep steady pressure and give her something to jig against.