I've always loved brainstorming sessions but I have also noticed they often don't produce much in the way of results. I attribute this to the fact that nobody

I've always loved brainstorming sessions but I have also noticed they often don't produce much in the way of results. I attribute this to the fact that nobody else (except me) would prepare for the sessions. Ideally the session would be announced a week or a month in advance, and people would be told to think about the problem and come up with some possible ideas or interesting aspects of the problem. Then at the actual session there is something to discuss. Too often people felt overwhelmed with meetings and would just show up and try to come up with ideas on the spot, which never worked well. Retreats are closer to my ideal and they seem to work better than brainstorming sessions. Weekly brainstorming sessions when you have months to come up with new ideas can work well also since they tend to start building on the best ideas that come up.