Reminds me of the joke I heard about the Fertility Awareness Method (FAM):

Q: What do you call people who use FAM?

A: Parents.


I can see how FAM might work if your menstrual cycle is extremely orderly. But for the other 95% of women...

At any rate, learning about FAM and tracking cervical mucus has helped me a ton. I have a very long and very variable cycle and I always used to freak out about "late" periods. Now I just wait and watch the mucus to see when ovulation happens, and I'm comfortable knowing that two weeks hence I'll get my period.