First, in the second paragraph it says:
I think it would be better if this were worded a bit stronger. Instead of saying 'they don't need to ask', I think it would be better to say 'they shouldn't ask'. And instead of 'editor can simply schedule', 'editor should simply schedule' would be better. 'Need not' and 'can' imply contacting the building scheduler is option but not mandatory. Since an event like this should always be put on a calendar contacting the building scheduler shouldn't be an option at all.For example, if the 1st Ward wants to use the pavilion on June 16 for a barbecue, they don't need to ask the building scheduler to reserve the pavilion for them on that date. Instead, a 1st Ward calendar editor can simply schedule their barbecue event with the pavilion selected as the location.
Second, I don't think the Primary activity is a good example. I would think that a regular Primary activity should be scheduled as an event. On the other hand if the wards in the building agree that 8-10am every first Saturday is available for 1st Ward activities (of any kind) and 8-10am every second Saturday is available for 3rd Ward activities that would be an appropriate use of reservations.
I guess in my mind that's the key to when to use a reservation: when wards agree on how to divide high-demand times between them. Individual wards shouldn't ask the building scheduler to make reservations for them. Reservations should only be made when the wards at a building make an agreement.
Of course, perhaps other's see it differently so I'm not as sure about this second suggestion as the first.