Yeah, my nesting box and coop color is insulated and I only have 1 cockerel that might get frostbite so when it gets under 20F I'll put it on him to be safe, since he's still pretty young but has a LARGE comb.
If you've never been to Wisconsin during winter, it's pretty cold. Starting to be 10F - 20F everyday. I did a good amount of research before I even had my chickens, and learned about the 'magic' of Vaseline! I don't know where/how to apply it, I just researched it is good to prevent...