I do spend three nights a week twiddling away on the turbo and I must admit I'm really feeling the benefits.
However, for me my weekly rides are also really important. Winter riding is all about the gravel bike. Not only do my rides get me out and about with fresh air in my lungs, but they also give me loads of invaluable bike handling experience on snow and mud.
In common with many others, icey roads do scare the heck out of me and I will either completely avoid them, or in the case of my commute, I'll set off 15 minutes earlier and take my time around the places I know black ice forms.