Birds are funny, mine have great roosts but prefer to sleep on a platform only a bit lower than the roosts, and the drape their wings over each other at night. I like the platform, too, they tend to place droppings at the back which I can scrape each morning, then treat the platform with a tiny...
We went through our first winter with chickens in 2008-2009, and it was a doozie- high winds, heavy snow, prolonged periods of -40C temps
https://www.backyardchickens.com/web/viewblog.php?id=7693-seasonal-concerns