Mick: picture a bicycle wheel on a horizontal axis--so that the wheel can rotate on a vertical plane.
Attach a golf club to the rim of the wheel tangent to its surface using some tape: so that as the wheel would rotate, the grip cap would move in a circle and would drag the club lengthwise as it did so. Picture the tire with the club parallel to the ground like it would be at the top of a golfer's backswing: the grip cap end pointing exactly the opposite direction of the target.
Suppose the left shoulder was the location of the axle of the wheel and the left arm was a radius or spoke of that wheel.
Clearly you can see how when the wheel is turned in the direction that pulls the grip cap, it resembles the action of a downswing, by moving the cap tangent to the surface of the tire--in an arc.
NOW, if the wheel gets moved very FAST, in a short time the throw-out force would become so strong it would tearn the tape right off and the club would become disengaged.
So lets attach it lightly with tape BUT with a hook and eye coming out OF the grip cap attached to the tire and wheel with wire so that it could NOT get disengaged. Spinning the wheel would pull the grip cap end until velocity built up enough to tear the tape BUT THE GRIP CAP END WOULD STILL CONTINUE TO MOVE - which from the golfer's point of reference, would be clockwise!
In golfswing talk and action, then, the left arm is moving the grip cap: BUT THE LEFT ARM ITSELF IS BEING PULLED AROUND by PIVOT action. Not horizontal action of the shoulders but VERTICAL motion because the left hip when it moves to the left without the head moving left at the same time CAUSES THE RIGHT SHOULDER TO GO DOWN AND THE LEFT SHOULDER TO RISE. Since the center doesn't move the left arm MUST GET PULLED DOWN, and with the left hand holding the shaft tangent to the arc in which the hand moves, it is the same as the wheel spinning and pulling the grip cap lengthwise.
THE PIVOT MOVES THE ARM. THE HAND AT THE END OF THE ARM IS A HOLDER-ONNER. THE SHAFT AND HEAD OF THE CLUB AT SOME POINT LATER IN THE SWING GETS THROWN BY OUTWARD MOMENTUM to where the clubhead "catches up." (A right hand on the club also gets moved by the pivot...)
Some people "watch the hands move while they exert their pivot to cause the arm to get thrown." This they call "pivot controlled hands." Other people are of the athletic type, or for the moment prefer to feel, that WHEN THEY MOVE THE HANDS IN THIS ARC THAT THE PIVOT ACTS TO SUPPORT THEM. It is a bit like "slide that cart over here, will you," where you FEEL THE CART WITH YOUR HANDS AND PUSH WITH YOUR HANDS, yet obviously your feet and shoulders are firm in support to allow it. You are exerting wrists, triceps, hamstrings... This kind of "use your hands and let the body REACT TO SUPPORT them" is called "hands controlled pivot."
Whether a given person today or tomorrow should choose to direct HIS OWN swing either one way or the other is, IMO, a personal preference, not a different procedure as such.
For example in another illustration, I can "move my hips, hence my torso, hence my arms, hence my hands and the club" by CONSCIOUSLY MOVING MY KNEES AND LEFT HIP and, with everything held firm in my body so that everything DOES get moved, everything attached DOES get moved by my legs. OR I might simply swing MY SHOULDERS -- hard and fast -- and in THAT process after the fact in replay I WOULD SEE -- WOWEE - MY HIPS AND KNEES MOVED and I wasn't even thinking about THEM - but they did what they needed to do to make my good swing possible.
The pitfall with a pivot-controlled hands swing is that we tend to get disjointed a bit like an erector-set device with the nuts not yet tightened. The hands and club "get stuck behind us." The pitfall with a hands controlled pivot is that we may NOT use enough body motion or weight shift to make a geometrically sound motion - and go over the top or leave out some of the resources available from our legs to power the swing. IF the handscontrolledpivot DOES TRULY CONTROL the direction the hands move - if the golfer REALLY DOES MOVE his hands correctly downplane and down the line as they need to be moved, the pivot WILL have to shift the weight, since it isn't possible TO move the arms correctly unless the lower body accommodates itself to the path the arms need to follow.
OK, that's the long version. The short answer to your query is "it's optional." Try both: whatever works. And Tuesday it might be different.
So I'd find the one that seems to work the best AND THEN USE THAT TO PLAY GOLF WITH AND STOP TINKERING.
