Menstrual synchrony
Strassmann argued menstrual synchrony defined as menstruation overlap should be quite common. For example, the expected difference by chance between two women with 28-day cycles—which is approximately the average length of menstrual cycles of women at the age —is 7 days. Considering that the mean duration of menses is 5 days and the range is 2 to 7 days, the probability of menstruation overlap by chance should be high.
Quintaglio Ascension Trilogy
The estrous cycle of female Quintaglios is 18 thousand days, and a female will hopefully mate 4 times in her lifetime every cycle, normally. There are some exceptions though, as Natova, and one of her daughter with Afsan, arose when 16 thousand days old. Also some females will often at the estrous cycle, thus having very low fertility. While male can mate at almost anytime, they have to wait for a chance, when a female is currently about to enter the cycle and accept the invitation. Females do not have to stick with one male every time, instead, they follow their instinct and choose the right spouse for the moment. Despite living on their own territory, the Quintaglios often have a long lasting friendship with the previous spouses, with the possibility of some forms of pair bonding.