Like The US Military in Afghanistan law firms operate in silos. Teams and departments don't talk to each other and don't sell for each other. Stanley McChrystal found a way to solve the problem by building a team of teams.
On a single team, every individual needs to know every other individual in order to build trust, and they need to maintain comprehensive awareness at all times in order to maintain common purpose—easy with a group of twenty-five, doable with a group of fifty, tricky above one hundred, and definitely impossible across a task force of seven thousand. But on a team of teams, every individual does not have to have a relationship with every other individual; instead, the relationships between the constituent teams need to resemble those between individuals on a given team: we needed the SEALs to trust Army Special Forces, and for them to trust the CIA, and for them all to be bound by a sense of common purpose: winning the war, rather than outperforming the other unit. And that could be effectively accomplished through representation.