Love all the suggestions around technical improvements - clocks, agendas, etc.
I'd suggest a more macro approach too. For the most part, my clients try to talk about the NUMBER of meetings vs. the VALUE of meetings. There is no number that's appropriate beyond value. People will go to 10 meetings a week if they're efficient, enjoyable, and productive without complaining of how many they're going to. They can go to 2 a week that are ineffective and wasteful and complain of having too many meetings.