There are roughly 6000 students of Jeet Kune Do right now.The main concept behind it was "the casting off of the useless" but the useful things still need to be taught.
You dont wake up one day and decide,hey I think Ill throw an absolutely perfect side kick,even though Ive never so much as seen one before.
There are things that need to be taught,but Jeet Kune Do,as does Ed Parker Ken Po unlike most other systems,allows for refinement and inovation by the actual instructor
Except for your personal interaction with your instructor,one Jui Jitsui school is pretty similar to every other,Ed Parker,and Jeet Kune Do schools can vary greatly,with only the base attributes being the same