I think the reading is a habit that developed as a consequence of the more essential need: having extra paper just in case. But, there could arise all sorts of theories as to why this did not also affect women. Maybe the additonal cloth in their clothing?
It can't be a time related thing, because women have more than enough time in the head to read most anything. In fact, if I had to spend as much time in a bathroom as women seemingly need do, suicide might cross my mind.