does this mean oral exams are the ultimate teaching tool? Something to loose (bad test score) + you have to be able to think on your feet and respond to questions (which I find broadly similar to teaching; it tests the depth of your knowledge).
To some extent yes, but in my ~1 yr recent experience giving oral exams (moved to Europe, coming from the U.S. university system that rarely uses them), I've found that students' personality has a larger influence on the process than I'd like. When oral exams work well they're hard to beat with another method, but the setting tends to favor more gregarious personalities with social confidence, and penalizes students who get very nervous or flustered in that kind of on-the-spot, face-to-face situation.
Being able to handle that setting is also a useful skill, of course, so you could argue it's fair to test. It's not the only useful skill, though, and it's not clear to me if it's being overweighted (even when I actively try not to). For example, in a computer graphics course, there are students who could do brilliant work if you let them sit alone for 60 minutes with a compiler (or with a piece of paper and some formulas), but who don't shine when examined orally, and vice-versa. There are some students who will do well in all modalities, and some who'll do poorly in all, but I think there's a significant number who will do differently depending on whether your exam is a 30-minute oral exam or a 3-hour take-home exam, so that choice really changes what you're testing for.
