I hit 0 leve allowances every other day. About 15 leves or less is enough to get me one level post 45 on crafts so it's by all means not useless to do them. Level 40, 45 and 50 leves will net you 2k+ to 4k exp per completion besides the exp you get while crafting required items. Add rested bonus, food and quality bonus to that and it's heaven!