My ideal setup:

Small teams that own and are responsible for products. Teams expose any information they need to share via APIs (including data for reports) Teams consume any information they need via other team's APIs.

My experience:

Teams that have 9-12 people on them, all working on different things/products, people external to the team completing some tasks that the team can't do, struggles to prioritize work since there is so many work streams coming into the team, members moving from one team to another, work moving from one team to another