Chances are it is all about the food. Late season trails that are being used tend to correlate with the HOT food source. I think the most important thing to know about the travel routes is what food they prefer early season and late season.

In my area they hit the beans and alfalfa early season and the corn and winter wheat late season. Oh and of course the white oak acorns early until they are gone then the red oaks all season. Just my experience lord knows I am no expert though, I still can't figure em out!