Every meeting that is planned requires what? Planning! The more number of people you have in the meeting, the more time it takes to prepare for effectiveness. A face to face may require jotting down some notes and questions, perhaps thinking how to phrase them to elicit the required information. But once you get into larger numbers... Think about how much preparation went into a keynote by Steve Jobs or perhaps a convention for housands of people by Tony Robbins in order to be absolutely effective!
How much time have you put in to preparation lately? Are you being effective?