[ce_me_golf]

Hardy's "idea" of a one-plane swing in TGM terms would be a zero-shift swing, meaning that the backstroke and downstroke trace a single plane. But Homer Kelley defined a few different planes that one can choose or is naturally inclined to use. The golfer is free to pick the one best suited, but the preferred plane (I think) is the turned shoulder plane. Kelley also described other versions where there are varying amounts of shifts, which would be akin to Hardy's dual-plane concept.

And therein lies the beauty of TGM it allows a golfer to apply a set of fundamentals he or she can use reliably based on their body type of natural inclination to do certain things well physically.

It's also the biggest problem I have with most other golf swing theories. Very seldom do these theories take into the consideration a person's body type of natural attributes.