PF slots and schedules are a key part of an airline business. If you are planning an airline then one of the key aspects of the plan will be a schedule and slots are an intrinsig part of the process. It does not matter that X or Y airport are not busy what matters is the time you need the slot for. To produce your schedule you need the slots and these are applied for for the season. As we know currently we are in the midst of the W12 slot allocation.
You need to look at what a key part of the business the schedule realy is. From the schedule you would set up your reservation system. This would give you the amount of seats avaliable so you can then get into the realms of ASK's RPK's etc. You can also start your engineering planning and crew planning all vital parts of the business plan and all required by your relevant aviation authority. I am sure Cyrano and Twin Ailse will also tell you how important slots are.