Discussion: I am 18 years old and have already had some significant romances. I wonder, how many sex partners are required to gain sexual insight about the desired partner?

I'll answer you with a familiar joke. One asks a friend how many eggs you can eat on an empty stomach. The friend thinks and answers five eggs. The questioner replies to him, you fool! After the first egg, your stomach is no longer empty. After the first partner, you may not feel that you already have complete insights about the preferred sexual partner, but practically, there is no need for more than a few!