I do ride all winter without studs. I am even comfortable going over glare ice as long as it isn't too sloped. That took a bit of practice, a couple of winters before I felt comfortable on it, and even then I go slow.

The practice would come on my days off when I'd ride through alleys while running my errands. They are not cleared like the roads and have much more ice on them.

I do thump into the pavement once or twice a winter when the ice is under snow and I don't know about it. Fortunately I can go on bike trails, or on streets with almost no traffic at the times I get to work. (I had to be there at 5 AM for one job, but later now.)