There are various "types" of Yellows. There's the Samitsu type who actually Heal and obviously have developped medical skills. Samitsu for instance was quite aware of nursing practices and all, and whether she uses it for real or it's mostly for show (I suspect the later... the herbs Egwene described were mostly used as aromatics and Suana is one of those who think joining the Yellow isn't really about Healing or healing talent but more about a mentality of problems solving).

Then there's the Romanda type (and, I suspect Suana), who see their role more abstractly and seem to focus a great deal more on making the world work as they think it should work, starting with the White Tower politics. This was more the Yellows I was targeting by my comments, those and known good Healers in other Ajahs unlikely to have but basic common wisdom regarding medical fact, and the main point was their "bullying" or forceful nature (doubled with empathy... for the apparent coldness, Romanda, Moiraine and Anayia all had this natural empathy too), as if the Healing skill was connected with a stubborn, forceful personality and empathy. What I was getting at is that the old type of Healing seemed to rely on different personality traits/nature than what Nynaeve does which is real Healing (but she also has the personality traits for old style healing too, and she was fine with it before she began to experiment), ie: based on principles linked to medicine, less a kind of act of will to focus all the remaining energy of a body on healing itself, with extra help of the OP. There are Yellows who have demonstrated a lot of skills using it - women with medical understanding who simply never dared to experiment like Nynaeve did, but obviously I had more in mind Romanda's comments that several Yellows, starting with herself seem to have little affinities for Nyaneve's "Restoring" methods, while novices who had been Wisdoms had a uncanny affinity for new style Healing.