Left; straight on; straight on; left.
Behind seat 15 and here lay the end. Through the door and into the morning air, down the steps to the back you went.
For the other half (myself included), we went straight ahead. Through the jetty and into the plane. Charming.
It's easy to discriminate by seat number. Really easy. And to save a few minutes in boarding, why wouldn't you?
And did it measurably help? Did it save any time, considering you had to open and close the back door, people walked further, etc.?
It's a slippery slope. Once you shave off a few seconds with seat numbers, what's next? Height… age… gender… colour?
To save yourself from ever having to stop, maybe don't start in the first place.