Hogs migrate a lot. I've seen them stay on a place for 3 or 4 weeks then move on and then sometimes the only stay around for a couple of days. They do tend to come back fairly regularly though. Now if you have something like a timed feeder station you can get them to hang around for a long time.
Quick note to the guy not wanting to let the corn ferment, Hogs LOVE fermented ANYTHING. You could end up with some seriously alcoholic hogs if not careful
