What a lot of people fail to realize is more vehicles are used in severe service use than many think.
With regard to salt, it is corrosive, perhaps when it mixes with water and becomes airborne from driving and evaporation the engine ingests it along with the air it needs for the engine to run. Maybe they feel that mix is corrosive to certain engine intermals and they want it out sooner rather than later. That makes sense to me.
Salty roads usually mean colder temps too. That means for many more idling, and less time for the engine to run at operating temperature. I'd follow the SS interval if it were mine.
With regard to salt, it is corrosive, perhaps when it mixes with water and becomes airborne from driving and evaporation the engine ingests it along with the air it needs for the engine to run. Maybe they feel that mix is corrosive to certain engine intermals and they want it out sooner rather than later. That makes sense to me.
Salty roads usually mean colder temps too. That means for many more idling, and less time for the engine to run at operating temperature. I'd follow the SS interval if it were mine.