Is the "random" boarding ordered by checkin?

I remember reading a study a few years ago that said random boarding is the fastest. But WN's no assigned seat strategy might still be the fastest because if an area of the plane is crowded, you simply walk a few more rows down where there is still more room.

Having elites board first is not a problem, though. Elites are experienced with flying so they know how to get their bags in quickly and take their seat.

The fastest boarding experience I ever had was on SFO-JFK a couple days ago. The 762 had mechanical problems and they were flying in another 762 from LAX. The delay lasted 6 hours. The gate agent said that the boarding had to be done quickly because if not, the crew will be timed out and everyone will be stuck in SFO until the day after. Passengers got the message and were so fast in boarding, quickly stowed their bags, and took their seat. Nobody was taking their time at all!