User blog comment:Xilinoc/Ch. 593 - Marching Out the ZOMBIES 4/@comment-1268838-20140820081640/@comment-5398287-20140820215451

Seems to me like the Superhuman Drug was basically only used on Szayelaporro because Mayuri didn't like his "I am a strong, perfect being who don't need no man" schtick and wanted to give him a gratuitously drawn-out death. Wouldn't mind it making a comeback (in a non-contrived way, of course - he would still have to get it into the opponent somehow), but that's just my two cents on it.