Under break-in, it just means no skid-stops, control wheelspin (not likely a problem with fixed) and forget carving corners. In fact, forget carving corners until spring.

In regular use, it's a lot like AWD in cars. People buy AWD thinking it will turn icy roads to dry pavement and then they drive as aggressively in January as they do in July. This explains all the SUVs you see rolled over in the expressway median. You seldom see a 2WD rolled over in the ditch. It's always 4WD and AWD drivers who think it's some sort of magic that exempts them from the laws of physics.

Same thing on bikes. Studded tires don't turn January into July. The best they can do is make it somewhat safer to ride in bad conditions. Even with studs, ride like you're in the TdF, and you'll go down.