I found that several tiers worked best for my main coops, basically acting as ladders in every corner leading up to the top tier, which was a grid, not a single bar.
The grid formation allows chickens of every hierarchy rung to roost peacefully together, and the supports that helped hang it from the cage roof prevented any of that nonsense where one chicken always wants to roost at the far right, but always gets up at the far left, always last at night, and then walks along smashing the others off the roost to get to its preferred spot. (You know the sort of behavior I mean, I'm sure, I just generalized to illustrate it better).
I always had more perch length than they needed, as different social groups, and fluctuations in the groups, would dictate that some wanted more distance between them and others at different times. Forcing them all to perch next to one another encourages antagonism.
The rope supports helping suspend the perches from the cage roof weren't necessary, they were more 'just in case' and also specifically intended to prevent chickens from walking from one end of the perch to the other.
That's the setup I found worked best for me and my chooks and turkeys.
Best wishes.