No, not all women take the pill and not all women have PMS. But, to NOT realize when your period is due is just plain stupid. There's no excuse for it. As I said earlier, take time off before you "think" your period is due. This is a business where women make their living off of their bodies and yes, they should be held to a higher standard because of it. A perfect example is this......if a lady makes her living from being an opera singer, you know damn well she's going to take care of her throat at all costs. Enough said.
As for irregular cycles, I don't know about you, but if I had them I'd talk to my doctor to see if there was anything that could be done. I'd hate to have that, it would interfere too much with my sex life as well as my "normal" life.