UMM, yeah always, even though its a pain with gloves.
But 2 of the guys I ride with never do. I think they are goofy!!
Although I had a friend get buried in a avalanche 2 years ago, he did NOT have his buckled, when the slide stoped we could see his helmet on the surface, before I took my beacon out we ran over to his helmet and starting pulling snow from under it. He was 8 inches under his hat!!!
I am not rying to say it is safe to rie with out your hat buckled but it sure helped us locate him FAST. He was ok.