Well that's difficult to say, but just imagine the following:
- you most likely haven't been trained for years in a submarine school how to attack shipping
- you just started using 100% realism
- you had bad weather
- you drive a Typ II
Guess your quota is ok.
The best of the best might do better - also in reality - Erich Topp i.e. sank 6 ships in two patrols with his Typ II but I have no ideas about the weather. Schepke only had two successes in three patrols. And as you know: those two belong to the best