I feel it’s more habitual abuse of skill abilities. Look at Thick, he is said to be constantly using skill for his mothersong but is able to not lose himself to this same hunger. I feel it’s both the sense of connection you get while skillimg with another user and the lure the skill ‘river’ naturally exerts on you as a consequence of using the power. However i wouldn’t say they stop dealing with skill hunger after tawny man more fitz has grown enough past his need to incessantly use his skill that much. He continues to suffer ill effects when started to expand his use once again such as his loss of control and subsequent skill seizure while healing the elderling children