[BerntR]

Good question.

In a lot of strokes (those who use the turned shoulder plane), the plane of the right shoulder turn and the plane of the club path meet at the top of the back swing. But since the shoulder rotate around your neck and the club rotates around your belly button - or thereabout - it goes without saying that the shoulder turn isn't directed at the ball - at least not at impact.

You can have a pretty steep right shoulder motion during the transition as you move your hips forward, stretch your left side and compress the right side of your core. So during that part, the shoulder will feel as it travels almost on plane. And certainly that it supports the on plane motion. Eventually the shoulder turn and the club path separates before they meet again in the follow thru.

I think it is vital to sense that everything that happens during the transition supports an on-plane motion. When you feel that your body wants to take the club to another place than where your hands wants to go, you know that you have a problem with your transition (which again may have been caused by some mishap earlier. I can usually feel it at address when I don't have the transition in order).

I have a very vivid feeling of starting the downswing on plane, and then bringing the club underneath my shoulder turn. Whether you swing or hit, you need some core stability and power package stability (the arms, the flying wedges) to get a good power transfer from the shoulders that are rotating high up around your neck down to the club that is rotated around a point somewhere around your belly button.