Blog is on pause, but please do enjoy my tweets :)
You could think finding number 51 would be a piece of case
But in this case there has definitely been 'something else' in the designers mind. -Standard paper size and/or some readymade mechanics might be the good guesses..
Definitely this is as far from user oriented design you can go. Infact it almost feels like it is deliberate internal joke, which ended into production..
Now compare to This one: