I know that it is commonly used to choke on the club and it works!! But i think that it is a mental thing. You choke on it and mentally you swing slower, maybe because the different feel on the grip. Mathematically and generally speaking (it is a bit more complex than this) a one inch choke on a club will cause a (on a 37" 7 iron and a guy with a 24" arm) a 1.64% decrease in the radius of the swing thus equal decrease in club head speed. This, on a 155 yds shot, will decrease it to 152.46. If it works for you then do it, if anytime time it doesn't now you know why. Having a 3/4 swing shots mastered is a plus for the game, its like 14 more clubs in the bag and help with this in between shots. Another way is to open or close the face a bit, lets say 5* to vary the loft of the club hence the distance. Compensate a bit in your stance for a draw or fade, that is if you don't have this new super forgiving clubs on the market that will fight the draw/fade. As mentioned on other posts, moving the ball in your stance, will also vary your distance/release of the ball. Hope this helped.