Probably the most annoying scrum practice are the sprint planning meetings. I've seen team after team hating scrum just because they were forced to spend four or even eight hours in a row making decision after decision regarding the content of the forthcoming sprint. The first hour of a sprint planning meeting is usually fine, but starting in the second hour team members were beginning to loose focus, they got irritated and rushed thru story planning. Recently I've read a brilliant piece in New York Times about decision fatigue that provides an excellent explanation why long sprint planning meetings cannot possibly work. The NY Times article reports about psychological experiments at several research laboratories that show that people can make only limited number of decisions before they got fed with decision making. I think the scrum community should rethink the practice of scrum planning meeting and replace this practice with something more efficient.