Caching Tiles at higher res

Thanks for a great app! I am trying to build up a high res cache of South Africa scenery using google. The other providers dont have decent resolution unfortunetly. At Min setting of 17, I get locked out without the load completing. If I restart every day after I get unlocked - will the cache eventually build up to have airport and surrounding city at max res? Or does it flush the cache if the load doesnt finish properly?