Originally Posted by
ethernal
Boarding speed is constrained by aisle space competition. The most efficient (fastest) boarding methods enable people in different parts of the plane to board at the same time (i.e, boarding a mix of some people in the front, middle, and back of the plane at the same time would be fastest).
Actually studies show that randomized boarding is fastest. Part of the reason WN is able to turn its aircraft in 30 minutes (free checked bags helps, too).