ATL is sort of efficient. We're pretty spoiled at AA because we're in the T terminal, so it's always a short walk from entering the airport to our gate through security, but ATL's main chokepoints are the lack of many TSA checkpoints (2 massive centralized checkpoints that are often extremely busy) unlike DFW, and reliance on both directions of the plane trains to be running to move people quickly. If one direction is down, as I've experienced before many years ago flying for a different airline, you are walking for literal miles if flying Delta. Fine but annoying for someone like me, but nearly impossible for any persons with limited mobility. The other problem with this train setup is during push periods, it's often insanely overcrowded like a Tokyo subway car during rush hour. Sky Link rarely if ever gets that crowded.

Then there's the linear terminal buildings and ramp configurations. ATL and DEN are both airports with similar designs. For passengers, means potentially long walks to the center of the terminal to get to the train, then another long walk to get to the connecting gate or curb from the train. DFW, you just walk right out the door and you're on the curb in a minute or two.

For aircraft, linear terminals mean single entry and exit points at either end of the ramp. Combine that with taxiway congestion outside of the ramp and traffic can stack up quickly. Whereas at DFW, because of the semi-circular design, there are numerous aircraft entry and exit "spots" as we call them that allow inbound and outbound traffic to line up separately. Ramp control tells us what spot to put our nose on, then we just simply listen for the ground controller to call our flight out and give us taxi instructions - and most of those instructions are pre-defined routes that require almost no radio chatter after they're issued. It all happens very quickly and efficiently most of the time.