I may be stating the obvious here, but I don't think anybody said this directly.
The 3 imperatives are directly related to the machine concept. They give control of the clubface, clubhead, and clubshaft. If we want to control the ball, we must first control the object that comes into contact with the ball.
So I see the 3 imperative as being the basic machine assembly. If any machine part (or imperative) is missing something must be compensated in the swing to make up for the missing part.
The 3 essentials make the already assembled machine more precise and consistent.
Trying to improve your motion without a properly assembled machine (or without the 3 imperatives) is like trying to use your brand new lawn mower when it is laying in pieces on the ground, or maybe it was put together incorrectly. So it looks like a lawn mower, but you will have a very hard time cutting that lawn if the blade does not spin, or there is no gas in the tank.
Great post, I like it a lot!
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"In my experience, if you stay with the essentials you WILL build a repeatable swing undoubtedly. If you can master the Imperatives you have a champion" (Vikram).
The reason you can't sustain the lag is because you are so eager to make the club move fast (a reaction to the intent of "hitting it far"). So on a full shot you throw it away too early, which doesn't happen for your short chip. (bts)