They should accomplish twice as much in half the time. Time is money. Track the cost of your meetings and use computer-enabled simultaneity to make them more productive. People wander off the topic. Participants spend more time digressing than discussing.
Nothing happens once the meeting ends.
People don't convert decisions into action. There's plenty of conversation, but not much candor. People make the same mistakes. Practice makes perfect. Monitor what works and what doesn't and hold people accountable.