and this, friends, is why it's often so hard to pre-book some things. People book multiple showings and then only decide to go to one. Other people get discouraged that they couldn't pre-book because it was 'sold out', don't show for the standby line and the theater ends up only 2/3 full because the multiple-bookers went to another show.
900 seat theater, 4,000 passengers, 4 showings of each show - there aren't even enough seats for every passenger to see each show if everyone only booked one showing, much less someone booking multiple...