I really need to see if my uni has a copy of my old essay on this topic.

Basically I pulled a bunch of data out of gamasutra post mortems and sort of reverse engineered the data towards optimal small team management.

My finding was similar. Basically its as far as you can go with a horizontal team in a single room.

6 Coders sharing an attic - good management outcomes and outsized performance

25 coders in 3 teams in a large office - bad management outcomes and communication difficulties.