The nice thing about quality studded tyres (Nokian Schwalbe, possibly others) is, the carbide studs won't disintegrate if you ride on bare pavement. It's not ideal, but you can do it. This enables me to err on the safe side. If in doubt, I'll just grab the dedicated winter bike with Nokian W106 Hakkapeliittas.

PS: I know and make note of 3 spots in my commute that have black ice earlier than everything else, when the freeze-thaw cycles start. When the route otherwise is just cold and wet, these 3 spots will already have black ice. It's some kind of combination of conditions in those places, but it happens year after year. Moral of this story is, ice conditions may vary greatly within just a few hundred meters, and you know your route and conditions the best.