While I would call them more energy efficient than lazy, Deer will take the shortest point between 2 areas. The caveat here is it must also be safe. They will go out of their way to stay concealed if they feel endangered.

In years where there is no acorn crop, the area is devoid of deer trail use. There has to be a reason for them to be there. In winter they can't meander back and forth nibbling if there's nothing to nibble on, so trails will be more pronounced.