If you work with a five element system, then the degree of specialization is severely limited. Theoretically, you could have 2 Fantastic, 2 Great, 2 Good, 2 Fair, & 2 Average. However I haven't seen a rule that allows you to retrain your specializations, which restricts you A LOT. Here's my math.
For the sake of simplicity, I'm going to replace the 10 things you can specialize with letters A - J.
A B C D E F G H I J
0 1 2 2 4 6 7 8 11 13
1 3 4 6 9 11 13
3 5 9 12
5 10
10
0 Is what you get by taking evocation. Numbers are Refinement numbers. So 12 is the 12th time you take refinement. If you can find a better pyramid please show me
Notice, you cannot take another rank at +1 because there's nothing for you to take it in. You can't take another rank in +2 because then you have 4 +2's and 2 +1's. You can't take another rank in +3 because then you have 3 +3's and 2 +2's. You can't take another rank in +4 because then you have 2 +4's and 1 +3. You can't take another rank in +5 because then you have 2 +5's and 0 +4's. So that's as high as you can get. 1 Superb, 1 Great, 2 Goods, 3 Fairs, and 3 Averages.
Unless there's some rule I can't find that would allow you to retrain this (and if there is please show me), or your table houserules it, then that's the inherent limit of Specialization. And even if you have some way to retrain, you're still locked by the theoretical pyramid mentioned ahead (with 2 in each step). So mixing and matching Item slots and specialization slots is pretty useful. And since it takes 10 refresh by my count for 1 Superb via specialization, or 3 refresh for an item.