Meeting, or work sessions are more productive if people come prepared. I make a habit of asking people to do some things in preparation for any meeting I am leading. I call this prework. The preparation is excellent way of getting the meeting going productively. By the way, I think work session is a much better term than meeting. Try it.
Often i will start the work session by having people share their prework. Depending on the results of the preework sharing, I can then decide the direction of the session. If people have completed the prework, then we can move on. If not, we must deal with the problem and determine whether there is any point proceeding with the work at hand. if people are not prepared, maybe they should not participate.
The work done in preparation for the work session really helps everybody get to the resolution of the issues and move on. In my meetings we always have next steps and part of the next steps is prework for out next work session.
In many "meetings" run by Project Managers, many people just attend as observers and not active participants. I suppose if they are simply information sessions that is OK but it sure seems like a unproductive use of time.
How many time do you participate in sessions where the participants are doing what should have been prework at the session? I think the session leader needs to address that with the individuals privately at first and publicly if behavior continues.
I need to Robert Schaffer of RHS&A credit for the ideas on prework and work sessions. Bob is one the wisest people I know about processes that work.