Why Does the Number 12 Occur so Frequently?

Eggs are packed in 12, there are 12 inches in a foot, there used to be 12 pennies in a shilling, the analog clock goes to 12. Why always 12?

A representation of dozenal multiplication table created by treisaran inspired Roman and Mayan numerals.

One of the first things I remember moving to the US from Norway years ago for studies, was how awkward I found all the measurements: pounds, inches, feet…