TIL that a brilliant physicist nearly failed his physics exam (sort of). What is revealing is the broad-based knowledge that was expected of any student of those times. Unlike the super-specialities of today. A career in such fields (rather in any field) in those days required total dedication to academics. Also the importance of oral arguments and oral debate.
Many programs still administer pretty general qualifying exams.
Mine was about two-thirds systems neuroscience (close to my thesis topic), with some reinforcement learning (in the Sutton and Barto sense) and genetics of autism on the side. You were strongly encourage to pick at least one topic that would be "mind-expanding" rather than just thesis prep work. My spouse's department instead had a thesis/anti-thesis structure. They wrote two proposals, the real one that they intended to carry out and a second one on a totally different topic. They then defended both.
Both were written + oral exams. I found the oral part helpful (fun, even) because the conversation keeps the candidate and reviewer from getting hung up on minor points, while probing how they think. Plus, I think there's a bit of tradition in making the candidate sweat by seeing how far you can ratchet up the difficulty.
What I am surprised about is the "practical" component. I've never heard of a hands-on exam!