Why are snooze alarms have an interval of 9 minutes?

I thought that it was only with my Sony Ericsson K700i that had this strange thing, but after mentioning it to Gladys (for those of you who don't know, Gladys is my girlfriend, and I also refer her to my dear), I learnt that her Motorola L6 exhibited this behaviour as well. Did you realise that when you set the alarm on your handphone, and press the snooze function, it delays the alarm by 9 minutes?

I was wondering... Why 9 minutes? Shouldn't 10 minutes or 5 minutes make more sense? So I just typed a search in Google for the answer, searching for "snooze 9 minutes". One of the best links I found is this one from The Straight Dope: http://www.straightdope.com/classics/a991126.html Apparently, this 9 minute snooze thing is in all digital alarm clocks. Out of all the explanations they gave, I find that the most plausible one is the last one, which had to do with the older mechanical clocks. They believed that the clock makers in the past had difficulties with the mechanical parts like gears etc to make the snooze function work at exactly 10 minutes, so they made the snooze function work at approximately 9 to 10 minutes. And this had affected the design of modern alarm clocks to have a snooze interval of 9 minutes.

Sometimes "traditions" are just formed this way. There are certain practices which we might not understand, and even prove to be impractical in this modern world, but we just follow them. Is this a good or bad thing? I don't know. What do you think?

Maybe sometimes we should just pull ourselves out from just being in this society and actually questioning certain practices and behaviours of our society, of what we have just been taking for granted.