Very little compared to Denmark - and for good reason. Salt won’t do you any good when the temperature drops below -10 C. Happens rarely in Denmark, but it’s a common occurrence in Norway. Which is why different countries take a different approach to keeping roads clean. Same with spiked tires. They practically don’t exist in Denmark. Quite common in Sweden and Norway outside the major cities.

The primary issue it the use of road salt combined with little usage of brakes due to regenerative breaking. Norway don’t have this problem as they prefer to use gravel. But geographies where road salt is a common occurrence during winter? Brakes should be cleaned on a yearly basis + owner need pay additional attention to actually use the brakes from time to time to clear out surface rust.

If you don’t? Discs will be pitted in no time which is an automatic failure at the German inspection.