Beyond that point, further reductions in effort and defects are small. Within that time range, you can balance time, effort, and defects to fit your business pressures. Small is better. Other things being equal, a small staff is more efficient than a large staff. It is more efficient because there are fewer interfaces between project members.
Staff spends less time communicating, but keep better informed.
Our metric observations have established the reality of small being better all along, but a couple of years ago we obtained data on 491 medium-sized projects. Fewer defects are better. There is also a time-quality tradeoff. When you extend your development time beyond the minimum, you score fewer defects. Sophisticated users are noticing that the first product to market generally tries their patience.