My candidacy exam was an hour. I had a half hour talk iirc, though it’s been a couple years since then so I can’t remember the exact time. The grad school told us to schedule a room for two hours, but my PI said there’s no way any busy professor wants to sit and listen to someone for more than an hour. He’s big on the idea that time is money and taking any professor away from their research is like wasting hundreds or thousands of dollars lol