[Mathew]

In a zero shift plane, the club would travel up and down the turned shoulder plane. In theory this is fine as far as delivering the sweetspot (a statement good enough for just now which is not quite true but unnessesary to add to the conversation), however the fact is that most clubs are not actually set up to be hit on this plane without tilting the clubface - one of the major directional factors. To exactly use the turned shoulder plane is not too easy in when trying to construct a model in terms of vector geometry yet the closer the golfer may come to this ideal, the less complicated the golfers alignments becomes.