I read the parent's comment differently from your reading. I read the parent's comment to say that there was stuff that was barely possible for the best studen

I read the parent's comment differently from your reading. I read the parent's comment to say that there was stuff that was barely possible for the best students to solve precisely in the time given, but that there were obviously-acceptable approximations thereof. And that either was a path to full credit. The professor's goal was to get the students to realize when to use approximations.