The problem with most instruction and/or methods is that they come from the perspective of a pro who, because they learned to play well as a child (via mimicry), are unaware of the moves and positions they get into to strike the ball well. They then concentrate their instruction on "feelings", setup changes, etc ... things that are not terribly important or successful in achieving a good golf swing. Give me 200 tour pro's and they will have 200 different setup's and 200 diferent sets of feelings about how they strike the ball ... all of which will be different than yours.
This is Paul's genius. He spent years trying to figure out why he was unsuccessful as a young teaching pro. He spent the time to identify the common positions of all great golfers, and then devised a system to allow anybody to achieve these same positions. He recognized that as adults, we no longer have the ability to ape our favorite player. His drills are specially created so as to overcome our evolved reflexes to "hit" the ball with our trail hand by start the DS with our trail shoulder and by straightening our trail arms/hands.
Paul was the first instructor to recognize this as the root of all swing faults, and the first to devise a set of programs that could be successfully used by adults to overcome it. And as you might guess, because we have to train ourselves to overcome our reflexes, the training is difficult and long. Like training yourself to learn a new language as an adult.