As Deming once said in regard to manufacturing inspections: "Inspection does not improve the quality, nor guarantee quality. Inspection is too late. The quality, good or bad, is already in the product."

The fact that software is "soft" makes it seem like this doesn't apply, but it does, not least because of the fact that once you have gone down the wrong path with software design, it is very difficult to pull back and realize you need to go down an entirely different one.