... not to mention that the head of a cock only has a finite number of nerve endings... regardless of the size.
So... on a small cock, they are all clumped together so a lot of them get flicked on at the same time.
Big cock means they're spaced out more... uncircumcized cocks are desensitised further again..
in short... if you have a small cock with a hood... you better be able to eat pussy like a champ...
but yeah... PC muscles are the trick... or some speed... although getting it up in the first place is difficult for some guys on it...