How many chickens can fit on a roosting bar?

I'm curious, could you please elaborate on the capacity of a roosting bar for chickens? Specifically, I'm wondering how many chickens can comfortably fit on one, considering factors such as their size, behavior, and the dimensions of the bar itself. Are there any industry standards or best practices that guide the determination of this number? Additionally, what potential consequences might arise if too many chickens are placed on a single roosting bar?