If all employees think exactly the same way, the size of an SEO Agency becomes immaterial.
I've cleaned up after enough large SEO agencies to know that linear thinking is their most common fatal flaw. Almost invariably the agency's founder ends up spending far too much time being an administrator, and not nearly enough time keeping abreast of Developments in the Wild, or physically conducting first-hand tests and experiments.
As a direct result the SEO Agency's core approach gets stale. 'The Edge' is lost.
Without its founder's ability to genuinely stay ahead of the sector and lead the way, the agency's staff learn by rote and mantra, instead of through genuine first-hand experience.
From there it's only a question of time before frequent serious blunders are made.
I've been fighting on the Front-Lines of Website Promotion since 1999.