There are several number based systems for stroke speed (PAT teaching for instance) and even in snooker there is a system like this, based on length of ball travel. It would be difficult to use any other method to objectively measure speed (technically it is possible, but not practically). This should not be confused with methods to teach speed control by various stroke mechanics. (Length of pull-back and follow-through, etc). That is not to say that one could not combine the two for an overall system of teaching and measurement (that would obviously be taylored to the individual).
One could for instance find the most comfortable and accurate speed for an individual to use, based on length and pullback of the cue and assign a value to that speed (for instance 5 out of 10, measured by length of travel). Then with that starting point it would be easy to find other, natural numbers. But if you are looking for a universally accepted speed measurement I think the PAT measurement comes closest.
One could for instance find the most comfortable and accurate speed for an individual to use, based on length and pullback of the cue and assign a value to that speed (for instance 5 out of 10, measured by length of travel). Then with that starting point it would be easy to find other, natural numbers. But if you are looking for a universally accepted speed measurement I think the PAT measurement comes closest.