I had a lot of success with grunt call in Woodville MS area. It really only works when rut is on and like FTF says, most of the time you get no response early in the season. But I can tell you the times I've had bucks come in they were in my wheelhouse before I could take the call out of my mouth and raise my rifle.
ETA: If you are hunting anywhere North of Baton Rouge , I would definitely be grunting every so often because when it works it's unbelievably cool. Maybe once series every hour.
This post was edited on 12/12 at 6:30 pm