When I was attuned to level 1 Usui, I recieved a "traditional" and a "non-traditional" attunement from the Masters who gave the class. I was also taught by another Reiki Master that the more attunements you have, the better because it will assist in stretching your crown chakra more.
BUT, having just one attunement is just as valid and may be as effective as 4. Who's to say, since this is all such an individual thing.
