alt Hacker NewsI always thought it's an optimization problem: the headstock is pulled by the strings towards the guitar's body, and whenever you get one string in tune, the change in (the distribution of) force changes the tuning of all other strings as well. So ideally they should be moved into an acceptable configuration collectively. People with six hands should be able to do it.
If you've been storing it with strings loose and are bringing it into tune you definitely gradually tighten all the strings rather than just doing it in sequence, for that reason