The Vulcan idea of not talking about pon farr always makes me chuckle, as everyone seems to know about it. It could very well be the worst kept secret in the Alpha Quadrant.
This is a tiresome trope of television generally -- something is treated as a massive revelation when it's first mentioned, something nobody knows about, this deep dark secret.
And then from that point forward, everyone treats it as common knowledge. This happens regularly in serialized drama, sadly. (To give another Trek
example, it was a big revelation that Data was created by Noonien Soong in "Datalore," but subsequent episodes like "The Measure of a Man" acted as if everyone knew who created Data all along.)