The Almost Imperative

[tongueblabberer]

What a great site this is. Congratulations, I feel like a kid in a toy shop or an equipment junkie in a golf shop.
Although a few years back a very prominent GSED told me it was Rhythm, I have voted for Extensor Action.
The FLW is the basis of Rhythm and all Lag Loading and Hinge Action have Angled Hinging travel and Rhythm. Extensor Action promotes , among other things, the correct RATE of clubface closing.
The checklist mentions it so consistently that it has definitely the credentials to be IMPERATIVE. This is only my humble opinion.