Yesterday afternoon I sat through a 3 hour briefing. I had one slide, which took me perhaps 3 minutes to brief. No questions, no comments. My slide was the 3rd or 4th slide in the deck, so for the next 2 hours 45 minutes I sat in an E ring conference room. I was all the way at the front, right in front of the huge TVs that were projecting the slides and the outstations, so I couldn't fall asleep or even slouch mightily. Sometimes I don't mind sitting through a briefing because it might be an opportunity to learn something, but not this one.
For my 3 minutes of talking and one slide, I estimate we spent at least 20 hours on it, tracking review and coordination meetings. Researching and typing the slide probably took me 1 hour.
We have another one of these, but I am on a special assignment for two weeks (not nearly as exciting as it sounds) so someone else will brief my slide.