That does sound unusual, to have the graduates drift away. The only comparison we have is UW graduation, also this weekend, also in the football stadium. The difference is, this was only 90 minutes long because the doctoral candidates were in a separate celebration the day before. Another hour would have definitely felt too much, as the poor grads on the field, in black gowns, would have melted. Once the speakers concluded, the actual “proffer” of the students as graduates by the Deans of the respective Colleges, and acceptance by the Chancellor, moved very quickly.