It is just as scientific understanding becomes more advanced, and more is discovered.
There was a lot of studies at one stage on how long sperm could survive inside a woman, and these were based on finding mobile sperm, and sperm only stay mobile for a few days.
Now it is known that sperm can and do go into a form of hibernation, and are live and viable, but NOT detected as mobile, and then reactivate at ovulation
Actually, this was known about in the past, in that observations of when sex occurred related to periods ( when nothing was known about ovulation) gave a greater window of likelihood to conceive, then when studies were dont on mobile sperm, that window was erroneously shrunk down to a very small number of days, despite the experiences of many women, who conceived without sex in that small number of days...
so again, I am afraid, a case of science being held up because things that women knew and experienced were ignored