What is your current design?
The main thing is that roosts need to be wide enough they can cover their toes in winter if you're in a cold climate. 2-4" wide is good. Then it is your choice whether to have them at the same height or staggered. If staggered, you don't want them close enough the chickens below can pick at the vents of the ones above.
This looks really nice! They all seem very content. My chickens use the ladder to go up but seem to always fly down. I am worried they are going to hurt their feet or legs. Their current roost goes up about 5 1/2 feet from the ground. I have removed the top two rungs so they can’t go as high and let me tell you, those girls have given me the stink eye ever since. They stand there looking for their top roosts and fussing... I don’t speak chicken but I can tell they are not saying nice things.
That’s what I have now except the diameter is probably too small. Do yours use the ladder to come down or just plummet to the ground like mine were doing?I use saplings or tree limbs, 2" to 4" diameter, and find it works well. Some of my birds roost up in the rafters, which are 4" fence posts, or 2"x8" boards.