Seems many winter Ultra riders skip helmets in favor of just hats and such, rationale is that the speeds are much slower and so helmet not as important. I would tend to agree, except for when on ice where you could be very likely to fall and hit your head. ...your thoughts.
I always notice the pictures from the fat bike races that people are barely covering their faces. Mind you many of the pictures are near checkpoints and start finish but rarely seems like anyone has googles.