Many people have wondered, and even lamented, about the iPhone snooze setting, which doles out extra bits of sleep in 9-minute intervals.
What's up with 9 minutes? Why not 10? Or even 5, for that matter?
It turns out, this was Apple's way of paying homage to clock history.
Back in the day, mechanical clocks had to offer snooze in 9 minute intervals because in order to make snooze work, the button was attached to the part of the clock that controls minutes.
The easiest way to engineer that, and give people the longest time to snooze, was to set it for 9 minutes, according to an answer on Quora.
The Quora post goes into precise detail as to how these older clocks worked and how they dealt with snooze, but needless to say, 9 minutes became the recognized standard for how long a snooze should be.