"So there is a "Clubshaft" Plane and a "Sweet Spot", or "Swing", Plane. But herein unless otherwise noted, "Plane Angle" and "Plane Line" always refer to the Center of Gravity application,. Study 2-N. Except during Impact, the Clubshaft can travel on, or to and from , either Plane because Club Shaft rotation must be around the Sweet Spot-not vice versa. So Clubhead "Feel" is Clubhead Lag Pressure (6-C) and is a Golfing Imperative. (2-0), If Lag Pressure is lost the Hands tend to start the hosel (instead of the Sweet Spot) toward Impact---the mysterious "Shank"..............."
And we sense this lagging sweet spot with the pp #3. Both ends of Lukes string.
While common sense would seem to suggest a shank is caused by getting too close to the ball , which maybe the case sometimes, this is another very interesting cause. Perhaps there is a chicken and egg relationship too? The loss of swing radius as a possible effect rather than cause? Swinging the clubshaft causing us to encroach, shorten our radius and shank?