Periods. Is there a method to how much and how often we bleed?

So I was thinking... those girls who only have their period for like 2-4 days and those girls who don't have a period often, yes I am jealous, but is there a method to why they bleed so little. I was wondering if it had to do with how fertile you are and what your genetic makeup looks like. For example, having more Testosterone in your system can make your menstrual cycle abnormal. So, is there truth behind the madness that is mother nature?