While talking about how it's often pretty relevant for researchers to know where a woman is in her menstrual cycleEmily Nagoski nevertheless keeps things in perspective.
[T]he literature on something like sexual interest across the menstrual cycle is far from definitive: while on the one hand there seems to be a small peak in many women’s sexual activity around ovulation, there’s a much more pronounced peak around the weekend. Context is a crucial component in understanding women’s bodies.
Source: Sex Nerd
In other word does it matter? Yes. Does it matter enough to be the holy grail some researchers make it out to be? You tell me.
Actually, while I think the main reason ev psychs and sociobiologists spend so much flinkin' time obesssing about women's levels of horniness has a lot to do with the paradigmatic inability to get that women are sexual creatures "just like people are," I have to admit that a more objective reason is that women's hormone levels are just a lot easier to track. They take a whole month to cycle! You can keep pretty much up to date with women's cycles by collecting pee once a day. Or even just daily diary entries. Women already frequently chart things like periods and ovulation. And there's lots of collateral studies one an surf data from, what with them being kind of intimately related to fertility or infertility, maternity, menarche and menopause, and so on.
I'm pretty sure the main reason ev psych and, for that matter, a lot of real scientists spend very little time thinking about men's levels of horniness is because a) men are considered the baseline normal against which women's libidos are measured and b) healthy men are assumed to be horny all the time so why bother? And also, given that on average researchers have tended to be straight men, eww, who could possibly be interested in horny men? But I have to admit that a more objective reason is that men have definite hormone cycles but they cycle daily. Which makes tracking them a heck of a lot harder more difficult: collecting hourly urine samples is doable but, um, distracting for most people. Especially if what you're trying to track are libido peaks.
None of that means that where women are in their cycles is completely irrelevant. Just that it's important to keep track of why there might be such disproportionate differences in available research.