Every team has rules, but few are intentionally crafted. This could have a negative impact. For example:
In a team of two, it's easy to create short back-and-forth emails. As more team members join, it becomes more complex keeping everyone in the loop. Emails may include reply-alls about weekend plans and real-time decision-making, leading to unread emails and lost information.
A single individual dictates the rules for the group. He may inadvertently communicate late at night that can affect an entire company.