1. Sometimes it is more efficient to use an exit or stairway that is not the closest one to your destination, if there are fewer people taking it along with you. In that case, you can make up the distance lost more quickly above ground than you would have managed if you had gotten into a long, dense line below ground.
For example, these past three months I have been commuting to the Houston Street station on the Seventh Avenue line. The King Street exit is substantially closer to my destination than the main exit, so I normally position myself in car 2, rear door, which is closest to the platform's emergency exit there and to the stairway on the southwest corner of the intersection. But if I have not made it into car 2 — perhaps only into car 3, which is nearest to the turnstile-exits at King Street, I will arrive at the south stairway too late to bound up it unimpeded. It will be clogged with a mass of slow-moving commuters trudging to jobs downtown from King Street, and I will have to slow my speed to match them. I prefer to avoid trudging if I can. Instead, I prefer to take the turnstile exit and then leave through the north stairway, which is usually much emptier at this time than the south stairway. Once I'm on the street, I can cross King in the downtown direction at normal Gotham Breakneck speed and be where I am going before most of the people who took the south stairway ahead of me have emerged.
2. Here is an example of striving to be second, rather than first, in a tight situation (see also this previous post). At King Street I try to be the second person out of the car, so that someone else can do the technically illegal work of opening the emergency exit; this particular emergency exit door is heavy and you generally need to push it once to unlock it and again to make it swing open, and I prefer to leave all that to the anxious person I choose to walk behind. Many people are in an intensely competitive state of mind when leaving the train for their jobs, and are happy to be the first ones to the door; this is the time to hang back and let them clear the way for me. Once the door is open, I can normally get up the south stairway well before them.