After chatting with DJI on this after I had posted the 200 sortie thing some time back, DJI defines a "sortie" as any flight, whether it be 1 minute, or 1 hour", despite the obvious difference in wear between the two, it was the best way for them to come up with 200. It also started with the Inspires "upgraded" prop system, that included hinged propellers, therefore the hinge points on the prop are what defined an actual lifespan. Whereas the Non foldable props have no defined lifespan.