I had a professor once who explained how this can be problematic: What about the handicapped or elderly? Will they necessarily take the same paths? How does the

I had a professor once who explained how this can be problematic: What about the handicapped or elderly? Will they necessarily take the same paths? How does the ideal foot path change in winter months when there is snow? Is it just based on the first person who plowed ahead and started packing the snow down? In the spring, would the path be different if it rained often and you could walk underneath a tree? This is not to say that the story is without utility, but that it can't be a universal maxim.