That makes you a feminist, don't be afraid of the label. Anyone read The Mists of Avalon? They go deeply into the mystical significance, and getting yourself in tune with the earth and moon so that you will be at mid-cycle at the full moon, and menstruate in the dark phases. But I doubt, even with the women-who-live-together-bleed-together effect, if all women of any village menstruated together. The segregation thing is a good point. Then, who'd make dinner? As the quaint saying goes.