How the maximum service interval is related to UAVs? I´ve been reading about the aircraft´s maximum service interval but this concepts is hardly related to the day to day aircraft (civil and military ones of course). How does this concept is related to UAVs?

Note: I´ve restructured the question, I´m sorry for the previous one
Service interval  - is a maintenance term indicating the interval (either in time or number of flight cycles) between two successive services (e.g. inspection, change of oil, etc.) that a component requires. 

In case of UAVs this is not different. It can be for example that the Service Interval of the engine is 100 hours of flight time, meaning that the UAV can fly missions for 100 Hours between engine maintenaince services.