Pitching is a skill that is vital to creating a score. However most go about this skill wrongly. You can change the length of your swing in order to control the distance of the shot. But this can take an awful lot of practice.
What you need to do is create a core pitch swing. In other words a swing that is natural shortened in length . Heres how to practice your core pitch swing.
Hit some pitch shots with any wedge just into oblivion. (a pitch swing is a swing that is shorter in length than a normal swing by some degree. The swing is also softer with less acceleration).
You will find that as you hit shots the balls will all start to group at a similar yardage. The idea would be to measure this distance and record it with the club you have used. This tells you how far that wedge goes with a (naturally shortened) core pitch swing. Repeat with your other wedges or short shot clubs and record the yardages also. This will build the basis for you to select the right club on the golf course.
Pitching in this way is more consistent as the pitch swing is naturally shortened making it far more repeatable and reliable. Trying to force your swing to different lengths can yield inconsistent and disappointing results. Why do you think the top golfers have a favourite yardage?
So work on your core pitch swing and lower your scores!