When I took my lesson last year, the instructor pretty much said that I now have a one plane swing. Not sure when it came about from learning 5 years ago. I kind of had a lousy year going until I finally accepted that I should go with it and see. My Handicap index went up approximately 10 strokes in the last couple years. After the lesson and just trying out the one plane swing, it dropped about 4 strokes in maybe 2 months. I knew nothing about a one plane swing prior too the lesson. The main reason for the lesson was that my hands and swing were terribly uncomfortable at the top of my backswing. Mainly trying to redirect the club on plane, when it in fact never left the correct plane. Not sure what the new year will bring when I start back up again.
Here is a useful site for anyone interested.
http://www.oneplanegolfswing.com/p3_...two_plane.html