Been looking through designs and ideas here and online. I assumed I would use a round 1-1 1/2" wooden dowel for roosting. I see a lot of simple 2x4 roosts. Some have just left the top side of a wall board accessible. Others have a shelf. Before I get dowels, I would like opinions. Do your chickens prefer round? Square? Flat shelf? What is a good roost width? 1 1/2 inches seems to be about right?