Dave..."If you cannot control the initial velocity of the cue ball, how can you expect any control of the cueball velocity after impact ? "
I understand your point of view Dave. But my point is that controling the CB (alone) to a two diamond distance, for example, has nothing to do with controling it for 2 diamond distance after impact OB impact. And besides, rolling the CB without OB impact is a foul!
Sure, controling CB distance (alone) is a skill and therefore can be practiced but with highly limited expecptions, controling CB speed (alone) has no practical application in playing pool.
Let me mention a drill I use that will possibly help to illustrate my point.
I place an OB in front of the right side pocket (when facing the head rail) about an inch from the jaw opening and place the CB an inch from the rail at the second diamond off the foot rail.
I shoot the down-the-rail corner pocket shot and attempt to control the CB roll distance in one diamond increments (within a 1/2 ball diameter tolerance...i.e. some part of the CB is on the line extending from the target diamond.
The head rail = 4 diamonds of roll and 5 diamonds would be a one diamond rebound back off the head rail.
After 4 diamonds, I give myself 2 ball widths tolerance...i.e. either the back or front edge of the CB must touch the diamond line...or VERY nearly so.
I can control the CB to within my tolerances through 6 diamonds of roll 85-90% of the time.
Then, I move the OB a ball width to the left and shoot the same drill but of course, there will be more CB roll when cutting the OB vs. hitting it square, so I need to adjust.
I first do the drill consecutively and then vary the roll...such as 1 diamond, then 3, then 5 then two etc.
THAT is the CB distance control I choose to drill on because, as noted above, controling the CB only...which certainly a skill as you point out...is not a skill that has much of an application in actual play.
Finally, a related drill I use is identical to the above except my mission is to contril the OB distance not the CB distance and doing so obviously requires an entirely different CB speed.
This drill is applicable to developing true pocket speed which is often crucial and is also critical for safety play where you need to send the OB to a specific spot.
Lastly, I set up 10-15 degree cut shots and try to control the LATERAL CB distance on draw shots. I am MUCH less accurate on lateral draw distances beyond 2 diamonds as would most people.
Taking this to the game table, if I need to pocket a shot and roll the CB, say 3 diamonds of distance...I KNOW what my 3 diamond distance shot is (easing off on my pace depending on the cut angle.
I guess my point is ...bottom line...there are very few drills I am aware of that don't translate directly to shots in a pool game and rolling the CB (alone...without OB impact) except for the lag...has so few actual applications in playing pool (because doing so is a foul) that I would rather practice drills that DO have practical applications.
Regards,
Jim