Assalamu aliakum, It is a misconception that all the ways are totally valid. As clearly mentioned by Mufti Abdur Rahman in Fiqh al Imam (I believe quoting Mufti Taqi Usmani) that there is only one valid opinion regarding every issue in the sight of Allah and no one madhab is totally correct. It is also mentioned in the book that the position of every madhab is "We are right with the possibility of being wrong and the others are wrong with the possibility of being right" - and it is because of this possibility that there is no condemnation.