Gobbledeegooked?
Thank you TC for your inspirational reply.
Perhaps my gobbledeegook was too gooky. The stats I would really want do not and cannot exist. As NL says reality vs perception is a big problem. Many conclusions can be drawn from stats, depending what argument you are trying to prove. The only true answer would come from stats covering exactly the same kind of work. In general singles are used when singles will do and twins are used when they are required so naturally their work cycles will be different.
Anyway most legislation comes from a perceived, and maybe not real, need for it. I am sure we can all think of rules that seem nonsensical, but someone perceived them as necessary.