Hmm, he can take Refinement for additional Items.
So one Refinement means +2 for an Focus. Maximum for his Foci is his Lore skill.
OK I see how he can get quite high...
Yeah, if you assume he's got a dedicated ritual room somewhere with two +4 Items in it, one each for Complexity and Control, he only needs Great Lore and Great Discipline, plus, say, Good Conviction, to manage 8 Complexity and 8 Control on bindings
casually and be able to do them at that level with perfect reliability in three rolls. Make that 4 or 5 rolls if he sticks a couple Aspects worth of prep on it and gets to Complexity 12 or 16. This only costs him 5 Refresh (2 for Ritual, 3 for Refinement), though it is handicapped by foci that powerful needing to be large, obvious, and obviously magical. On the other hand, it's thaumaturgy anyway, so he might not care about that.