I know it's just your opinion, but it is based on misconceptions. It doesn't matter whether or not you ovulate at the same time every month, because it's not the rhythm method. You are actively looking for signs of fertility every day, so whether or not this happens at regular intervals is irrelevant. It is the fertility signs and not the time of the month that are important. As to the effectiveness of charting, if used properly, its effectiveness approaches that of the Pill if used properly or is only very slightly less - I have seen stats with effectiveness of the Pill being around 98% and charting around 97%, or thereabouts. It is more effective than many barrier methods. Charting mostly fails because people take chances or don't get the hang of doing it properly, so I would say that if you want to rely on it alone you need to be very committed and very strict.
For myself personally, I have always tended to have irregular and long cycles, and I am also strict about when I want to have babies and when I don't. I have been very committed to charting and have not used any other BC. I have only gotten pregnant when I wanted to, and then almost immediately, and I have never had a pregnancy when I did not want one - granted, it's only been 7.5 years, but so far, it has worked for me.
Nothing other than abstinence is fool-proof...not even hormonal BC.
Get used to me. Black, confident, cocky; my name, not yours; my religion, not yours; my goals, my own; get used to me. -Muhammad Ali