How can I get the schedules to fill equally?

The scheduler tries to fill the slots so students aren't conflicted.  The scheduler does not take into account balancing the schedules.  Most schools “tighten up” the schedules by removing slots before they run the scheduler. 

For example, if you originally had 16 slots available, but you only have 10 students to schedule, remove 6 slots from the schedules before the scheduler is run.  This will ensure that the schedules wind up even and starting/ending at the same time.