Jeff Mcbride always said, pick something and do it really good instead of trying to do everything...
I think that you should have a good foundation in the basic concepts, perhaps a better question would be about how many CONCEPTS should a flourisher know or be proficient at, and I would say, at least 7 or 8.
then the number of moves quickly reaches that inifnity mark, because once you can understand fanning, it doesn't take more than a minute to learn something like palmback fan, and if you see some new fan from Jaspas or something, you can probably just pick up a deck and try it and bust it right away!
so definitely learn 5 or 10 basic moves, in each concept .