That could have an adverse effect depending on said penis size.
On one hand the girls might see his cock and if it's a micro penis start giggling at him and turn away.
When I 1st read this I was going to reply "Nah, a painless and no stretching out their vagina session (so it's becomes too loose for the next guy) causing the next guy to take too long so they will never turn him away"
Then I re-thought it and "Yes, they may turn him away as a micro penis will not generate any friction for the guy and he will take forever to finish reducing their assembly line throughput for the day"
Or if he has a third leg, besides hitting some other monger in the head as he swings it around, the sheer size could scare the girls away.
I've had
a small percentage (maybe 1 in 10 new ones) of girls, when after I handed them the, ahem,
"the entrance fee", and I took off my clothes exposing genius jr in all his glory, hand me back my money and tell me to see another girl. No rashes or sore on me and I'm not a John Holmes by any means so maybe they are just too tight. So perhaps your statement is correct.