Most of the spellweaving spells are best boosted by getting a level 6 focus. Way more, it seems, than getting from 100 to 120. So - is there really any good reason to spend 20 skill points to get to 120? I like being at 100 since I can then bridge an Arcane Circle with people whose sill ranges for 80 to 120. But if someone has a good reason to try for 120, I would love to hear it.