You're looking at this all wrong. Taking 20 years to develop an airframe is fully intentional. The whole point of that project is to keep military contractors in business in peacetime because if war breaks out it will be much harder to start a company from scratch. If the company were efficient and pumped out aircraft like a normal company the government would be stuck with thousands of otherwise useless machines to maintain. By dragging out the development for decades they can keep the engineers employed without burdening themselves with enormous O&M costs.

Obviously this will have to change if war breaks out for real, but in theory they won't be scrambling to hire people and will have at least some production capability. They will be scrambling to expand the production lines, but they won't be starting from 0.

A lot of people see defense contractors as an enormous waste of money, but to the government it is a strategic investment.