My wife & friends and I discuss this as we weave through the passenger zombies who seems to think it's a strange and mysterious practice. It bemuses me to think that most people would be aware of the general security protocol (both domestic and international), yet they seem ill-prepared to briskly move through security. When they get to the belt only then do they decide to take off their watch and then proceed.....opps....., forgot that laptop....... so they take out the laptop and now head to the secur......hang on.....have to remove my keys and phone from my pocket, better add those into the tray, now on to......hold it! Gotta dispense that one litre bottle of hand sanitiser they're carrying...... and so on.
Morale of the story is the queue shouldn't be a meritocracy for those who arrive at it first. ;-)