In physics in college we were grilled in verbal discussions with professors and an assistant for ~30 minutes or until the professor had found the limits of our

In physics in college we were grilled in verbal discussions with professors and an assistant for ~30 minutes or until the professor had found the limits of our knowledge, one I had went on for 50 mins. The entire grade of the diploma was composed of all the verbal tests and the grade of our thesis (pre B.Sc.) - so there had to be a point where you knew virtually everything well enough to explain it at least in one way and derive some relations or sketch a derivation if prompted to. The flaw here was the personality of professors - some were easy to piss off, others more patient.