There's also little variation in how it's done, and only three versions really spring to mind - the grouping system, the seat row system and the mighty free for all that has made many a budget airline boarding process SO enjoyable, as long as you enjoy passive-aggressive (or just aggressive) elbow up in your business of a morning.
It probably comes as no surprise to find that none of these systems are particularly effective or efficient, although surprisingly, it's when people are left to their own devices that things speed up. According to this article, we don't need our movements micro-managed by the airlines, and letting us choose our own seating destiny can shave up to ten precious minutes off the boarding time. It goes on to detail random, outside-in and theoretical methods that save even more time, and asks just why airlines aren't even deviating from the standard method, show to be by far the least efficient.
Seems to us no matter which way you want to get onto a plane, some things will always hold true. The privileged will always get to board first, and sit comfortably in their sky thrones as the rest of us stumble on, some parents will always try and get on with their ten year olds when 'traveling with infants' is announced and even if the main body of the passenger list boards in a seamless ballet of efficiency, chances are that some genius is still dawdling in Duty Free and will hold the whole plane up for ten minutes anyway. Still, it's nice to dream.