it was very common to fly a MAX and NG in the same day. Plenty of times we’d go from a -700 to a MAX9 one after the other. That being said their is very noticeable changes IMO from flying the MAX8/9 to a regular NG along the pitch and roll axis as well as switches in auto modes doing completely different things. Not a massive difference for the average line pilot who doesn’t have intimate knowledge of the systems but they are there. My original answer to HK was simply you can’t just spin the entire pilot group up rapidly to fly the MAX. The most logical way is to implement the MAX training during CQ which another poster stated. HK proceeded to tell them off as if they were clueless on the topic and brush it off as something that is nothing to worry about. I just wanted to clarify that it was not the case and that it would be prudent for the airline to qualify most pilots in the fleet early instead of getting caught with their pants down when the jet finally does show up. Which sounds like is slowly getting closer and closer.