Why Is Defense Acquisition So Difficult?
It starts at program conception and then moves through demilitarization and disposal. As you can see it is a rather complicated process with several major reviews. At each review a series of documents must be prepared that explain and justify the program and make sure it is meeting all regulatory and statutory requirements. As such for a large program it can take a small Army working several years to accomplish everything.
The other issue is that the amount of testing required also may affect schedule. For a program to advance through the steps it has to pass it tests. Fail a few and that may add months to your schedule. In defense acquisition especially time is money. The longer something takes, the more expensive it is.