If I were graded solely on quantity, I would produce stuff that only just barely passes the bar of being a pot. (If you take a clump of clay and stick your finger in it, you basically have a pot.) Therefore, I think the story is false.
But then you'd get sick of making such shitty pots, if you liked pottery as an art form enough to want to learn it, and you'd start trying to make better ones because just passing the bar probably wouldn't be enough for your sense of aesthetics/craftsmanship (or maybe it would, and then you would have learned something as well)
It depends a lot if it is a voluntary art class, or you are forced to take it. (Or it is the only job you could get, and you are not to interested in it.)
True if all you care about are grades (which are what? A badge?). I'd probably knock out what I needed to pass (make it through the gate) and then focus on improving.
Nice story though.