More and more bus rides at JFK to get deplaned off DL-NW flights means usually waiting for all passengers to deplane before being able to make it to the terminal building to get on your way. [Passengers are at the mercy of the slower/slowest passengers in terms of how long it will take to actually get into the terminal building.]

If you are connecting at JFK and it happens to be one of the DL flights operated by AF onto which you are connecting landside, then beware that the boarding pass(es) issued at the originating airport may not be accepted by even the non-TSA security line dragons and you'll have to re-check-in with AF at JFK to get the new boarding pass(es) since they seem to believe that boarding passes issued by the likes of even DL-NW are not applicable to get airside.