To improve impact and straighten your shots, here's how to use the intermediate-target drill Jack talked about. Pick a spot on your target line that's about 10 yards in front of the ball. Have someone watch to see if your ball passes over that spot. If it goes right of it, your ball position might be too far back in your stance. If it goes left of the intermediate target, then your ball position might be too far forward. There's only one position in the swing where the clubface is square to the target line.
There's a difference between the finish and follow-through positions, and understanding that will make you hit better pitch shots. A pitch swing should end at the follow-through position, defined as the point past impact before either the left elbow or both elbows bend. The finish occurs when the club's through-swing momentum ends naturally.On most pitches, you shouldn't swing to a finish position because the ball will fly too far. You also cannot decelerate to reduce the distance, because you'll likely hit it fat or thin. But by swinging to the follow-through position, you can still accelerate through impact and regulate distance.