This sounds a lot like how my PhD oral qualifying exams went. Except I got 30 minutes of highly technical questions from all 6 committee members and then sat o

This sounds a lot like how my PhD oral qualifying exams went. Except I got 30 minutes of highly technical questions from all 6 committee members and then sat outside for 40 minutes while they deliberated if they should let me stay in graduate school (they did). After that I got to have two more personal interviews with more in-depth questioning. The whole ordeal lasted somewhere around 5 or 6 hours.