Magic diversity

[Zenzei]

Just wondering if there's real definition for this often spoken term.

-How many different magic paths accesses do you need to be considered magically diverse?
-How many mages do you need in any given path to be considered diverse in that path? Is one good mage enough?
-How strong your best mage in given path must be to be considered diverse in that path?
-Does magical diversity serve any other real purpose except item forging and SC summoning?
-As many spells & items require two different paths, what are the most desirable path combinations when thinking about magical diversity?
-Any other important factors regarding magic diversity?

I realize these are quite broad questions and probably impossible to answer accurately but some general guidelines should be possible to make.