I like in between 5-8. Preference. I can TRY more, but it's gonna be a stretch. That being said.... Just because a man owns a 747 Jet does NOT mean he knows how to land it. That is the bad side of some men who are endowed... the ones who lack technique.
If a woman says, "Go slow." You are probably out of her typical size range & should take heed. After all, the ride will go a whole lot better if you get a pussy to cooperate (Pleasure/good sensations= natural lube & stretching Vs. pain = drying out/lube stops/tightening down pain reflex...)
Some of the best sex I ever had was from a little skinny white guy with an average length and under average girth, go figure! I think it's more about dick swinging technique myself... at least if there's enough to "stroke the sweet spot."
Another note: Most guys in the hobby are on average 3-6 inches, maybe your off nomers of 7+.... but they're rare. At least around my neck of the woods. Can't wait to expand my .... horizons. lol