You want a little less distance than what you normally achieve with a club without changing your swing or trajectory.
You are taking deep divots with your irons.
You need to improve controlling the ball and gain better touch and feel for your swing.
You want a low, spinning lob shot or you need better control over the distance and direction of your iron shots.
You want to get a better feel controlling the height with of iron shots.
You shank the ball.
You want to learn how to control the height of your iron shots.
You swing too much with your right hand if you are right handed or left hand if you are left handed.
You are overusing your body to compensate for inadequate hip and shoulder turn, poor wrist cock, contact, or balance.
You contact the ball with the neck of the club or shank the ball when using your irons.