Our chickens love the 2 by 4's and my husband says the wider ones are better for cold climates so they can keep their claws warm by sitting on them in the winter.
We have 6, 20 week old chickens. 4 like to roost on the low bar, 1 likes the high roost, and 1 likes the poop shelf! Our roosts are staggered 2 by 4's so they don't poop on each other. We LOVE having a Ring camera in there. VERY entertaining!