I'm probably in the minority here but I actually believe that Oral Boards are the only worthwhile exam that we do. I was absolutely terrified of this exam from day 1 of residency, I was miserable studying for it and would never want to repeat it, but the process of going through it really did consolidate my knowledge and working through cases with colleagues gave me a good opportunity to see how different training/SoC can be across institutions. This is something we can only acknowledge to ourselves in retrospect once it is completely behind us considering how painful it is going through it (successfully) though.
I am not a board examiner but my interpretation of the test is that is a test of competence, not excellence (a cliche but a true one). Sometimes assessing competence involves assessing how you work through a problem that you are not expected to know the answer to. Some cases are straight forward and you are expected to know the answer to these, but many cases exist in grey areas, much like in real life. How many times have you had a case pop up in tumor board that was out of the ordinary and you had to frantically look up a reasonable answer on your phone while it was being presented? In these scenarios you may be lauded if you know the answer but the real expectation is that you don't hurt a patient if you don't. We are the cream of the crop [for the time being]. The emphasis on the socratic method in residency means that we are used to getting answers correct and we are far too hard on ourselves when we get answers wrong. It also conditions us to think that if someone is asking us a question, there is a correct answer that they are looking for.
The best answer in these weird non-standard of care situations is to vocalize your thought process, your concerns, and what you would do to reach a conclusion for treatment without causing undue harm. This is what we do in the real world as well. On my exam I had two cases with a nodal recurrence after radiation (one in the axilla, one in an obturator node after prostate pelvic RT) and I was PUSHED on what I would to do for both and it was immensely frustrating both times because how could I be expected to give an answer without a composite plan, DVHs, discussing with medoncs, discussing with the patient, etc. These are scenarios that if any of us have in clinic, it takes us hours to decide what to do and to evaluate the plan (or it should). These are not scenarios you fail because you don't know what to do, because no one does. There is no standard of care!
So, as much as we would like to have an exam where we are tasked with contouring a low risk prostate or evaluating a set of tangents for DCIS, if this was our expectation then no one would learn anything and this exam would truly be worthless. Exams are meant to be difficult but passable with preparation. This one is and the consistent pass rate is evidence of that. I know many people that left their exam thinking they conditioned a section or two at best and wouldn't be surprised if they failed (myself included), and all of them passed on the first try. The examiners acknowledge that sometimes you have a bad day, and so you can condition a few sections and have an annoying but relatively easy retake. Sometimes people have a REALLY bad day and need to retake the whole thing. It happens, but considering the number of board certified radoncs that I wouldn't trust to give HO prophylaxis to my pet chinchilla, I think that the bar of competency is probably set at a reasonable and achievable level. I'm sure you did better than you think, most of us do.