If you're in a country where there's is snow or just cold temperatures, you don't "randomly" have 4 extra tires. You literally need them for at least a few months. Typically you'd swap over in late October, then back in March/April depending on how it's going. Swapping them yourself is trivial enough, but it's also incredibly cheap to get them swapped at a shop.

Note that at least last I checked, the proper transition temperature isn't "freezing" or "there is snow", but about 7-8°C. That's when winter tires will have better grip, and summer tires grip steeply diminishes below this. Once there is actual snow, your just actually up shit creek with no paddle on summer tires. But if you have to emergency brake at like 3°C for example, it makes a significant difference what kind you got on your vehicle.