I think the source of your confusion is that you're a one man team. You don't have to solve problems that 20-man teams have to face. At least half of all the code I depend on is code I do not understand, so I have to depend on its tests, and I have to make the same promise to consumers of my code. If my change breaks code someone else wrote that I didn't foresee, I am depending on his tests to tell me what I screwed up.
Maybe the problem is that you have the 20-man team. There is no coherence in the code. The design is wrong, coupling is too high, and the module cohesion is too low. The large team makes certain that is the case no matter how "tight" (aka heavy) your quality control process.
I have found from working in large teams, there is a core four who get things done. The rest are simply dead weight dedicated to shuffling paper and attending meetings. At best, they do nothing. At worst they create more work than they do.
Use the right four and dump the other sixteen. You will get at least ten times more productivity and ten times higher quality without even breaking a sweat. If you don't have the right four, you are hosed from the start.
This works fine if you are tackling a problem that can be sufficiently addressed by 4 developers. Depending on the size and scale of the problem you are trying to suggest and the time line required for delivery you may need a larger team.
When you begin to take that into account you realize you have to find ways for the larger team to work together and still produce a quality product. Hence the techniques being used by the author and other companies out there trying to address similar problems.
"...you have to find ways for the larger team to work together and still produce a quality product. "
I am not sure its possible. The communication overhead of so many linkages forces incoherence. The resultant incoherence forces still more additions to process and body count. That adds still more communication overhead. The result is still more incoherence - not less. If something is "finished", its simply because time, money, resources, and toleration ran out. The end result was simply called "done".
Maybe that is the best we can do but I am hard pressed to call products produced that way quality products. See Vista et.al. for instructive detail.
