Good posts on this. I might add that the hen to gobbler ratio can complicate things as well. In some areas of MO where I hunt, the hen numbers are so high, I hate to set up too far away from a roosted bird. If I know he's alone, I'll try to get within 75 yards or so and maybe only call once or twice before he flies down. Just enough to get his attention. Many people call too much at a roosted bird. Just let him know you are there when he's in the tree. Then when he hits the ground, pour it on 'em and get your gun up.
WM