All I do is a double check of everything. Is the food full, is the water thawed, is the coop door secure, is the bedding clean/dry/full, is everyone there and active and perky by day, is everyone in the coop on the roost by night? That's it. They do just fine. Chickens can't feel the "wind chill" when in their coops, there is not wind inside, the temp is the temp.
I brought mine in. I do have rabbits out there and I could not get into the run today. Everything is ice. I had to bri g several buckets of warm water to melt a small area to open the gate. They have heated water bottles but it doesn't help if I can't get to them.
The netting is really low due to the weight of ice. I am so putting up a roof over the run. Lesson learned.