In my experience having meetings that make you lose the will to live. I had to sit there for hours with people that like to waffle on until the end of time.
I took a course in Organizational Communication in grad school on my way to a Master's in Communication Studies. That semester course answered that question very well. I would be happy to sell you my notes for a reasonable fee.
Whichever one keeps you out of trouble and let's you take credit for all the good stuff.
Whatever is appropriate for the situation, seriously. One has to judge their audience and how much CYA you need.