Gen Con doesn't actually have set slots, like some cons do. There are games starting on the hour, every hour, all day long.
We have a room with 12 tables, and I staggered the games so we have 6 events starting every two hours from 10 AM until the Tournament starts at 8 PM (At which time, all the tables are booked for the Tourney). This way, chances are most folks can find a good starting time that fits in with other event scheduling.
It also helps a little with organization, as it means we don't have 84+ people (12 Tables with 6+ players and a GM) all getting up and leaving at once, while 84+ more people are trying to file in at the same time. And it makes it a little easier to arrange free time for the GMs to attend other events as well.
Bull