Very large legal departments find it difficult to create a one-department culture. With hundreds of lawyers and as many support staff, often scattered hither and yon, professional cohesion dissipates, let alone social cohesion. The notion that humans evolved in small groups and can’t effectively sustain relationships beyond a certain limit is noted in Chris Anderson, Free: The Future of a Radical Price (Hyperion 2009) at 40. The book refers to the Dunbar number – “the empirically observed limit at which the members of a human community can maintain strong links with one another.”
According to Wikipedia, Robin Dunbar is a British anthropologist and evolutionary biologist, best known for formulating Dunbar’s number, roughly 150, which suggests a “cognitive limit to the number of individuals with whom any one person can maintain stable relationships.” If your department reaches this scale, you may need to nurture sub-groups, below the Dunbar number in size, to better cohere the department’s awareness of each other and shared values.