I could see this working very well for Southwest, though, for instance, as they already have everyone pre-line up not only by lettered zones, but also in groups of five within those zones (eg "B 15-20") at most every Southwest gate they service.

Instead of milling around the gate in the 15 minutes before boarding, they get everyone where they're supposed to go, and then funnel them through the door single file, in order. As the article references, though, it breaks down into a clogged jam-up of humanity trying to stuff their carry-ons into the compartment the moment you get to the plane.

I'm not sure this would work very well with Southwest because they don't assign seat numbers to passengers (at least in my experience). Most of the time, the people at the front of the group choose seats toward the front of the plane and hold up everyone else while they're stowing their bag.

I've been on an airline where they line up individuals in a specific order (there's number markers along the line at the gate to make it easy). I don't know what the algorithm was, but it seemed fairly efficient.

At every airport I've ever been they are smart enough to call the next zone before the previous zone's line is half way done. And even when the line dwindles, the next zone people are all huddled around and ready to get on.

Perhaps the 3 subsections they present is too many; imagine it with 2 subsections resulting in 12 groups. Using an organized line-up system like Southwest, you could reduce the ready-time. First, groups 1 and 2 would line up. Once the group 1 line is clear, group 3 would take its place, then group 2 would load. This would also reduce the number of people per lineup, something that in small terminals still plagues the Southwest system (with their 6 effective groups).