Paul, it all depends on the use and the condition of the engine. Figure that the same engine configuration is used in Canada without AC and in Florida with AC. I suspect MB designed for "worst use conditions" (Florida summer traffic with AC on).
Here is another interesting fact. The carbureted MB 250C engine ( w114 Chassis M130 engine) for the USA never used a oil cooler. The same engine in a 250/8 sedan (W114 chassis, M130 engine) for the USA, always came with an oil cooler. Does not make sense.