I just started doing BJJ again, and am aching like a mofo for it. I love it. Martial artists often declare that they know hundreds of techniques, but are rarely pushed to show it. I like this anecdote:

Master x said to Master y, how many arm bars do you know?

Master Y then started to talk through this one and that one.

Then Master x said 'no, show me'.

Master y then started to demonstrate step by step on a student.

Master x then said 'no, show me while grappling.'

Master y then grappled with his student, and out of the 30 odd arm bars he knew, he only successfully applied 5.

Master x then concluded, 'you only know 5 arm bars.'