well no, I can get the information on site since I live in my town and know how the streets are treated. And there are cities following different approaches like e.g. not using salt on smaller roads and footways but gravel and sand instead. and they do that each winter, no matter how conditions are. but you are right often it is a on time decision. but that doesn’t interfere with my idea: if you know the local authorities use plowing, salt and sand depending on weather conditions, then we tag that they use those 3 types. The basic concept behind the idea is to have the quantity and quality of winter service, and thus monitoring and including as much information as possible. in the end (for example) a navigation software could include those information and form - according to their own interpretation - a street rating… if you have low temperatures and a street is not salted but only plowed you should probably avoid the street when having bad winter tires, even if they plow 10x a day. and if you are in a wheelchair a path with gravel and sand as winter service might be not as appropriate to use compared to a salted/plowed one. with an old timer you might avoid heavily salted roads or roads with gravel since it will hurt the bodywork (ok if you are really anal about the condition of your old timer you won’t touch it during winter
). the road surface will be different depending on winter service type (And many other variables!), no matter how often you service it.
I just like to distinguish between quantity and quality of winter service. that gives us more flexibility and information content.
oh and in addition the winter service tag should be enough flexible to include those salt/gravel/sand boxes you often have on footways and sidewalks. maybe an amenity tag is better suited for that. but at least the type of content and so forth should be congruent with the winter service tag concept (reusing existing tags/prefixes/suffixes).