and considering a guy is thickest at the base,I imagine you wouldn't want him to be too long
It's best if you and the gal match up so that at his deepest most urgent penetration you might experience a "tinge" of pain
so when he is balls deep his thickest part is stretching your most sensitive area about the opening
also too many women like the feel of the ball sack banging against them
hard to accomplish this with the average gal if you're better than 8 inches