The scheduler only overloads the schedule or requested number of positions at a service if the team or family is bigger than the maximum number of required positions in any weekly service.
For example, say you have two service times, 8 AM and 10 AM. At 8 AM only 1 Usher is needed, but at 10 AM 2 Ushers are needed, and you have a two person family qualified only for only the 8 AM service. MSP will not overload the Sunday, 8:00 AM service to fit these families in. The scheduler is not smart enough to realize that they do not have the Sunday, 10:00 AM service as a preference, and therefore it should not really count it since they can never really be scheduled there!