What we need is optimum sizing for effective functioning. Optimum is defined as the most favourable or advantageous amount for a particular situation. The optimum width for a garden bed is twice the distance a gardener can comfortably reach. If I am tall and you are short, your optimum garden width will be smaller than mine. The optimum size for a flock of chickens is around thirty birds.
Chickens loose their social structure when the flock is too much bigger.
Smaller flocks can become unsustainable in numbers over several generations without human protection and assistance in raising the chicks. Similarly, the optimum number of inhabitants for sustainable human settlements is seven, then thirty, then around eighty, around 250 and so on. We humans have optimum sizes for working in groups. When we want to make decisions, a subcommittee of three is very effective. For a discussion group, seven is the number which gives everyone the opportunity to say what they think.