I think every coder does their own lane. One front end, one back end, one Android, one infra, one UI/UX, and so on.

The second hire in a lane is usually a manager-tester-QA, whose primary role is communicating with the other lanes. Communication is awfully distracting and time consuming, but often a bottleneck as well.

Also most code starts off a bit hacky. That's the way it should be. It gets refactored once it's confirmed that the feature is needed.