It becomes increasingly difficult to obtain each subsequent level... I believe that resetting skills and abilities is an unnecessary and undesirable feature, because in order to replace them with something else, experience is needed, a lot of experience... a memory mentor is only useful if a witch has acquired an unsuitable skill in her hut, or if you REALLY want to acquire a skill with a hero who cannot do so due to their initial set of skills... But the drawbacks of the skill wheel cannot be fixed in this way.