Two winters ago I hit a patch that had no sheen whatsoever, completely invisible.
It was just after sunrise. Air temp was about 34F, and we'd had dry weather for weeks. But it was in a spot in a park that never gets direct sun, and I think a thin frost had formed there.
I hit my face, broke a tooth and bit all the way through my upper lip.
I still commute in winter, but I still get nervous when the temp hovers around that freezing mark. And I no longer lean into curves when it's cold.