Yea, its just an operational philosophy, cultural thing. Same thing with the emphasis on who can touch which switches.
Northwest operational philosophy seems to have been a bit more highly choreographed and regimented. Delta cockpits were more flexible. Work together and "just make sure somebody does it" was kinda the attitude.

Its sorta like the old saw about the Air Force/Navy difference.
Air Force: You can't do it unless the book says you can.
Navy: You can do it unless the book says you can't.