Anthropologist Robin Dunbar famously suggested that humans can interact personally in group sizes no larger than about 150. In the late 1980s, Freddie Mac went from being what I call sub-Dunbar to super-Dunbar. When an organization is sub-Dunbar, it can operate informally. If I want to make a decision, I can call all of the people who might be affected. When an organization is super-Dunbar, I no longer know everyone who is going to be affected by my decision. A super-Dunbar organization needs formal procedures or else suffers from widespread miscommunication and employees working at cross purposes.
It is possible for a super-Dubnar organization to continue operating informally. It can compartmentalize, so that the effects of decisions remain sub-Dubnar. Or it can establish a system of shared values and common patterns of behaviour, a culture so to speak.