Unfortunately, there's no easy answer.

Every tom is different, every situation is different, and the birds' mood changes throughout the season. One day, a tom might come on a dead run, gobbling his brains out, to aggressive calling. Another day, or even at another time on the same day, that same bird might run away from aggressive calling.
It generally best to err on the side of less calling. I know that is really hard to do when a tom gobbles back to every call you make. Definitely avoid doing any more than a few soft tree-yelps to a roosted bird. It's a real rush to have a roosted tom roaring at every call you make (they usually gobble best on the roost, as they are trying to assemble their hens below them before they fly down). But, the more you call to a tom on the roost, the more likely he is to stay in the roost and wait for the hen (you) to come to him. The same can happen on the ground. If you call continuously to a gobbling tom, several things can happen. He could think you are as excited as him and plant himself, waiting for you to come to him (which is the way it's supposed to work in the wild). Or, all his gobbling will attract a real hen - in which case it's game over for you. Or, if he has hens with him alot of aggressive calling may drive his hens away from you (you are competition for their tom, and hens don't usually like that). If the hens leave, ol' Mr. Longbeard will follow them about 99.9% of the time - and you lose again.
There are occasions where aggressive calling will get a tom really fired up. Often though, they'll clam up as they come in. That's typically the best thing for you to do as well, because the more you call to a close tom, the more likely he is to pinpoint your location and see you moving (while you are calling) - then you lose again.
Aggressive calling can occasionally get a boss hen ticked off and bring her to you. That can be an effective tactic, but it doesn't happen all that often.
If you know a tom is within 100 yards, soft clucks and purring will be most realistic to him. You would be amazed at how far away a tom turkey can hear even the softest calls. I have had birds gobbler back from 200+ yards away, at just one soft cluck. Don't fall into the trap of thinking you have to tear out your loudest yelps/cutts on a box call, just to have a tom hear you. Unless of course it's really windy and the tom is upwind of you. Boy, it is a complicated (and interesting) topic.
I could go on forever, and never give you the right answer for the next particular tom/situation you run into. The real solution to turkey calling is simple - hunt a lot, learn from your mistakes, and don't get discouraged! Use your instincts to tell you what to do next - those instincts will improve with time. It's not a science, it's an art and no matter how long you hunt, you'll never make the right move everytime. Even when they beat you up and make you feel like you are going to go crazy!
