As the fellows who would know best have said rattling is a tactic that varies in it's use depending upon what part of the season your in.At home (New York State catskill mountains) Doe to buck ratios are seriously out of whack,I hardly ever rattle and if I do I either mimic light sparring trying to get a curiousity response.If I knew that I was in an area that held two dominant bucks I would go at it more aggressively depending upon what part of the season I was hunting.
Where I hunt out of state every year rattling is a very effective tactic.Like any game calling I believe your first sequence should be light,you don't know how close you may be to a cruising buck,especially if you are in an area with limited visability.
I will never forget the first time I rattled in a nice buck,he came crashing through the woods with his ears laid back,fire in his eyes.I looked down at the antlers in my hands in disbelief,Holy s--t this rattling stuff is for real!
It is about as exciting as it gets! Good luck to you!