No matter what the number of levers that is used or how the player employs a release, the swing has to be timed correctly. However PSM is an absolute must when using the Traditional Swing.
PSM ( proper sequential motion) is when all of the elements of the swing are assembled in their correct order. PSM is experienced when the golfer hits an extremely solid shot that goes further than expected, yet the execution seems effortless. That's when the linkage system is operating most efficiently....good levers, good release, good timing.
If we take the force of the swing to it's source we’ll find that once the player has loaded the gun- that is when he has reached the top of a fully wound backswing....there is a series of sequential movements like a domino chain that produces a power-efficient swing...
The feet and knees lead by transferring the weight, followed by the hips and the lower trunk, then the back and shoulders and finally the arms and hands. Yet the feeling is that 'it is all together". By timing the sequence in this, there is a summation of forces with each part contributing some share. When the body parts fire in precisely the correct order and the correct amount, the best swing is produced.
One hears golfers use the words rhythm, tempo, timing yet although they are probably referring to their to timing, these three -rhythm-timing-tempo are not the same. To set the record straight and avoid confusion of these terms.
Rhythm in the movement arts means harmonious flow resulting from proper relation of the parts. A rhythmical swing "looks good". However it may not be as productive as one of lesser beauty.
Timing is the sequence of movement.
Tempo is the rate of the movement fast-slow but has nothing to do with sequence.
One could have a fast tempo but still be in perfect sequence. His swing may have perfect timing. But may not be considered rhythmical. Good rhythm and tempo are desirable but timing is the critical part and by far the most important part.