GAO has made some suggestions to NASA about how it could better manage future programs, including Vision for Space Exploration:

GAO’s recommendations include requiring that NASA projects demonstrate:

• that key technologies have reached a high maturity level before approving the projects for transition from the formulation to the implementation phase,
• that the design is stable before approving the projects for transition from the design phase to the fabrication, assembly, and test phase; and
• that the design can be manufactured within cost and schedule and meet quality targets prior to any decision to enter into production.

Sounds about right to me!