Around here there are to many doe, especially in 2D. IMO, rattling alerts more deer and makes them hesitant to come in than it does attracting them. I know quite a few good bow hunters in our area, and almost all of them say that rattling around here isn't very succesful. I admit I do it myself a few times threw the season.
Try it when things are slow, start out soft and work your way up. Remember, dont try to sound like a couple 180's fighting to the death. Its unrealistic especially for our western pa deer.
My best response has been when I rattle first thing in the morning when its light enough to shoot your full range. I think the woods is quieter then and the sound carries better. Mix in some grunts and get ready.