You can set up services and resources in Microsoft Dynamics CRM to take into account different-sized facilities or the experience levels of your users when a service is scheduled. This is known as capacity scheduling. Capacity is a relative unit that you define. For example, you could define capacity in a bicycle repair shop as the number of bikes the shop has room to accommodate at the same time. If a repair bay has room for four bike-repair stations, the repair bay can accept four bikes for repair or inspection at the same time.
Capacity can also measure skill level. For example, a junior bike technician has the ability to perform one bike inspection per hour, and a senior technician has the ability to perform four bike inspections per hour. If two bikes must be inspected in one hour, it takes either two junior technicians, or one senior technician who can perform the inspections in half the time.
When you add effort required into the selection rule, every time a user searches for an available service activity time, the selection rules inspect the resources for capacity available. If the resource is scheduled, then that resource's capacity is reduced by the effort required for the service. This is repeated every time that a service is scheduled requiring that resource, until the capacity is exhausted.
Capacity is defined in the resources working hours. Effort required is defined in the service. You can think of capacity as "how much money you have" and effort required as "how much something costs."
For example, the repair bay has a capacity of 4. A bike repair requires an effort of 1 and a tandem bike repair requires an effort of 2. The first time the repair bay is selected, its capacity is reduced to 3 for that time. The next service activity scheduled is for a tandem bike. This reduces the repair bay's capacity by 2. The repair bay has the capacity of 1 left, which means it could accept another bike repair, but not a tandem bike repair.