I see your point. If the 30% usage under stressful conditions is taken, then the examples given of "pipeline patrol, fish or game spotting, aerial applications, police patrol, sightseeing, livestock management, etc." would very likely make up 30% of a C210s life in Australia.
Putting it in "Severe use" and back to 2500 hrs inspection.
Less likely for a C177 which may well have been privately owned for recreational flying.