Is there a forth "LAG"?
 

The "clubface LAG", the torque of (or resistance to) the rotation of the forearms (or clubface), along with the other three: pivot, auccumulators and club.

#3 Accumulator Lag
 

In his recorded GSEM classes, Homer Kelley never referenced Clubface Lag, so we have no "official" authority as to its existence or non-existence.

Personally, I would classify the phenomenon you describe as Accumulator Lag. Specifically, the effort of the #3 Accumulator (Left Hand / Clubshaft Angle) to maintain its In Line condition (Left Arm and Club / Rhythm) during the rotational Overtaking process, i.e., the Overtaking of the Hands by the Clubhead during the Release Interval (Release to Follow-Through).

#3=dual lag
 

Thanks for the reply. So, the #3 Accumulator actually takes care of the clubhead and clubface simultaneously.

The #3 Accumulator And Clubface Control
 

The Right Elbow actuates the Roll of the #3 Accumulator and, in that sense, is both Clubhead and Clubface control (6-B-3-0). However, if Clubface Control is left solely the province of the Right Elbow, unintentional variations in Right Shoulder location and Right Elbow bend at Impact will disturb the Clubface alignment (2-H). Therefore, it is best to use Hinge Action, i.e., the Flat Left Wrist held vertical to one of the three Basic Planes (Horizontal, Angled or Vertical), to supply the veneer control to the Right Elbow's actuation of the Clubface.

In other words, the Roll of the #3 Accumulator determines the length of Clubhead Travel from Impact to Follow-Through. This Travel, in turn, determines the amount of Clubface Closing (the longer the Clubhead Travel time the more the Clubface closes). But, that amount of Clubhead Travel must agree with the In Line condition of the #3 Accumulator as dictated by the Flat Left Wrist and its Hinge Action.

Hence, Horizontal Hinge Action will produce the longest Clubhead Travel (and a Full Roll of the Clubface); Vertical Hinge Action will produce the shortest Clubhead Travel (and a No Roll of the Clubface); and Angled Hinge Action will produce a Clubhead Travel somewhere between the two (and a Half Roll of the Clubface).

In The Golfing Machine, the differences in Clubhead Travel produced by the various Hinge Actions is known as...

Rhythm.

:)