That's a little surprising. I wouldn't say it's the norm by any means because in reality T8 is utilized much less than T4 or T5. AA (and most airlines) already build in a ridiculous amount of extra time to their schedules so that they can still arrive 'on time' even with a significant delay. The reality is that JFK needs to be more heavily slot restricted to reduce frequencies on domestic flights and force airlines to use larger equipment with fewer movements. That's the only way to get the disaster that is JFK (and the rest of the NY airports for that matter) to operate relatively on time.