Let’s imagine your guess for the next wait time was always just the length of the previous waiting time. If you always guessed the previous waiting time, how big would your error in guessing the waiting times be, on average?

An informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.