Da Boss wrote:
You could probably play it either way without making any impact on the game.
It affects to how sorcerer uses his/her improvement rolls. For example: Sorcerer Theleb has high speech 86% and rune casting heat 84%. If we use rules as intended then he can raise his rune casting skill only to 86% no matter how many improvement rolls he uses, but if we take the latter interpretation he can raise his casting skill to max 89% with single improvement roll, although he can't use skill's full percentage till he has used improvement roll(s) to high speech.
It's not a big difference, but it makes improving magical skills bit slower, which is IMHO a good thing.