^ This. The most chaotic part of the whole process is finding your number in the line-up to scan your boarding pass. They also set your expectations on seat-finding as you board, so if the plane is half empty or full up, you'll be able to make a good seat choice.

While the other airlines are announcing the 15th class of partner airlines rewards members being able to board and everybody's standing around watching, Southwest is loading planes.

OMG yes...I flyed United occasionally when SW doesn't makes sense for the route. I was even status matched to "Premier Platinum" for a while. I was amazed that 1. I didn't get upgrades due to the remaining levels above me, and 2. Just how long boarding is and how many special groups. Can't see the business value there.

Southwest is AMAZINGLY efficient, and driven to streamline everything. This is the reason they transformed the whole industry by turning planes around in 15 minutes when their competitors were taking hours. If Southwest is doing it, it doesn't mean it's absolutely the most efficient way, but it's probably close, and you can bet they've seriously thought about alternatives.

Speaking of efficiency, Southwest in two airports now has managed to get a 17-minute late-check and an 18-minute late-check on the same plane that I also somehow miraculously got on (and was the last person if I remember correctly). Pure magic.