[MizunoJoe]

There would be no mistake of swinging the club on a single plane with zero shift, it is just not common and most players are not capable of this. Ideally the golfer should create a two dimensional, flat plane, once he bends the plane line it becomes three dimensional and precision is lost. The plane line should not change, the golfer should always swing along the plane line but not necessarily the flight line.

I don't see how this could possibly work, as the shaft rotates around the sweetspot, which is the thing that should stay on some plane. If the sweetspot stays on a plane, the shaft cannot.