[O.B.Left]

I tend to agree. However, a small but important implication is that in case of a center-shafted club the shaft plane = the sweetspot plane.
Therefore, we can go further and create a variable weighted toe/heel of such a club and see if e.g. with a heavy toe/light heel center shafted club (imitating the proportions of a standard club to a degree) the shaft plane still equals the sweetspot plane.

Cheers

Not sure I follow you 100%, but Id think that with a heavier toe the sweet spot would move and you'd be back to a non aligned shaft and sweet spot.

All of this begs the question: Why arent there face balanced , center shafted irons? There must be a very good reason. We must need the rotation perhaps? Or is there something else? Homer suggested the long nosed, low profile irons of the 1930's were a delight to hit.

I've sort of struggled with tracing conceptually as there seemed to be a parallax issue. I now realize that while I was swinging the sweet spot, I was trying to trace the shaft plane. Lukes point about tracing the sweet spot plane, the imaginary string from #3 to sweet spot is insightful. Like pointing your finger at a bird in flight, tracing. This way I am aiming that which I am swinging, the sweet spot!

Per 2-F PLANE OF MOTION. "Regardless of where the Clubshaft and Clubhead are attached it will always feel as if they are joined at the Sweet Spot---the longitudinal center of gravity, the line of pull of Centrifugal Force."

Regards
OB