We worked with BoostFM to capture their concert for promotion while also capturing 10+ interviews all within a 6-hour window.  We were able to move quickly and efficiently with a well oiled 5 person crew to capture great-looking content in a tight timeframe.  Crew size is often determined by how tight the shooting schedule is, while one person might take 30-45 minutes to load in and set up a great looking interview shot, a larger crew can execute faster and at a higher level.  You also end up with more people paying attention to a more specific task.  For instance, a dedicated audio mixer solely focused on capturing the best audio, a camera operator focused on keeping the shot framed and in focus, a producer to make sure the correct content is being captured and a gaffer to make lighting adjustments quickly and efficiently.