I find that after 3/4 hour in almost all presentations, I want to escape. Often much earlier, rarely later. I expect that a presentation should make its main point in the first five minutes, so I am not trying to figure out where it is going, and it should not have gaping holes (namely, deep problems that you are sure must have occurred to the speaker and are not addressed). I work in a policy school, so we might be preached to about a policy's virtue. Just tell me the main ideas, the foundations for your claims. Preaching is for other contexts.
And your opinion, about virtually anything, is less likely to be of interest than your evidence and argument.
In the 1970s Paul Meehl published an essay, Why I Do Not Attend Case Conferences, in his Psychodiagnosis. I could not do better than Meehl.
One other thing. If you (I!) cannot get through most seminars without leaving exercised and irritated, it's time to stop going and maybe go to the movies instead. If you have to go, learn to sleep quietly, without snoring.
