>>81935585
>How much does dick size matter?
Depends on this: has she ever had a PIV orgasm?
No: will only depend on her social circle
Yes: It will depend on how deep you gotta go for that particular woman to reach the Anterior&Posterior fornix. The depth can vary on her vaginal size as well as how well trained her vaginal muscles are.
Yes(Short answer): starting from 5 inch it's possible to achieve. Safe spot around 8 inches (yes, unironically).

>And can a girl get over an ex with a huge cock?
Only if you can reach the fonix spots.