Scrum teams are based on 7+-2 team members, the main reason behind this theory is the lines of communication. That socially we can only maintain x number of relationships. The addition of each team members adds to the lines of communication exponentially. Based on the formula Formula = n(n-1)/2
One of my team current has the following make structure and I find myself ensure that everyone communicate with each other.
|Projects||PO||BA||Dev||QA||Team lead||IM||IT PM||Architect|
|Project 1||p1-PO||p1-BA||Dev 1
|Lead 1||Scrum master||PM 1||Arch-1|
|Project 2||p2-PO||p2-BA||Dev 4||QA 1||“||“||PM2||Arch-2|
|Project 3||p3-PO||p3-BA||Dev 5
27(27-1)/2= 465 lines of communication, excluding releasement management and operations, etc.
“Ideal team”: 13 people = 78 lines of communication is the end goal, weather, how and if this can be achieved is a debate on how the the underlying principles drive to this outcome of team structure.