system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: For what reason is the snooze timer set to 9 minutes instead of 10?
gpt
Original mechanical alarm clocks had already been standardized by the time the snooze feature was invented, so gearmakers had to mesh the gears with the existing clock mechanism. It worked out that they could best fit a gear set up of about 9-10 minutes, but the opinion at the time was that 10+ minutes was long enough for people to properly fall back asleep, so the nine minute gear configuration was chosen.

Then digital alarm clocks came around; while easily altered to whatever snooze length is desired, they had to compete with mechanical ones and most people already expected a nine minute snooze. That was what stuck.