Are we talking strictly technique? There isn't even agreement on classical piano technique, let alone jazz technique. Different approaches work for different players. Lots of classical pianists got into trouble with all of that "lift the fingers high" and "turn the thumb under" stuff in the Hanon books, which were the main classical piano technique books for decades. As someone who plays jazz piano and has also studied classical piano, I can say that there are situations in jazz that the classical technique books don't truly prepare you for. On the other hand, if you're a jazz pianist, spending a lot of time with the classics won't hurt you.