It depends. There are some pests that are highly mobile. This means they will not live and breed in one place. Instead, they will travel from one room to another or within a residential building. A pest control company will first determine how severe the pest infestation is. If the infestation has spread too much, the company will need to find and destroy the source as well as the infestation itself. In this case, multiple treatments will be required for complete pest removal.