There are several factors, needless to say, even if it's the same person counting, the # of licks will differ at each attempt.
If you wanted to look at it semi-scientifically, the number of licks needed depend on these factors:
* Pressure per square inch the tongue is applied to the surface of the tootsie pop (TP)
* The average amount of square inch in contact between tongue and TP
* At what measurement from the center of the stick of the TP at which you declare that you have reached the center of the TP.
* The rotation factor of the TP - if the eater continues to lick one specific portion only to reach the center faster - or if licks are distributed evenly around the outer surface area of TP.
And to a lesser extent:
* Ambient temperature
* Use of teeth / or lack of teeth of eater
* Hunger of TP eater
* Boredom of TP eater
* Age of TP