Let me take a stab from the contractors perspective or at least from the division I work at within a top 6 Defense Contractor. I would love for any Government agency to start the conversation with their budget and schedule constraints and let us tell them what we can do given their parameters. As the author stated, industry is usually pretty good at meeting schedules. However, this scenario is impossible when there isn't agreement on the Government's end on what they want to acquire.
In the example above, our company could say we can build you X in 9 months for Y dollars. Yet, unless the Government knows it wants X and not X+10, it doesn't matter.
In the end the two questions posed by the author are really similar to mass opinion that if the Government knows what it wants and doesn't change its mind, then the acquisition timeline can be reduced. Stop changing the requirements and save time, money and get things faster.