They just don't understand the 40 years of the menstrual cycle!!
I noticed a while ago on another forum, that an SP unexpectedly had a period during a booking and it put him off punting for 2 years! He saved himself 2 years worth of punting money and we saved ourselves from meeting a dick.
We don't always get a warning that the monthly is going to happen, especially if hormones take control and we end up having a twice monthly one, which has happened to me and had to cancel loads of bookings!
The nice ones understand!