A US Army Colonel commented once that he always did his old job for 2 years. He served with the Weapons Systems Evaluation Group (WSEG) which was co-located with the Institute for Defense Analyses (IDA) which was known as DoD's "think tank".
The US Army had the Research Analyses Corporation (RAC), the US Navy had the Center for Naval Analyses (CNA), and the US Air Force had RAND which made all the others necessary.
I worked with the Army Colonel on a project for the newly established US Army Operational Test and Evaluation Agency (OTEA) while I was employed by BDM (bought TRW except automotive part) which is now Northrop-Grumman.
My model became it takes good people about a year to notice that the new job is different and about a year to "work on" the new job. I thought "new PhDs" could probably do this. [All particle physicists at the time were probably "bright enough" to do it.]
Charles J. DiBona, who became (former Governor of Colorado) John Love's deputy when they created the first version of the Department of Energy. Mr. Di Bona was of the McNamara whiz kid variety who had resigned his commission in the US Navy (as a Lieutenant Commander) to become President of the CNA while I was there.
One benefit of leaving high energy physics as a profession I expected was that things could be completed in less than 5 years.
It is very difficult to see significant change in 5 years. The easiest changes to observe are related to related to wars or terrorist acts.
Eliot Richardson was a Republican with a fabulous resume during the Nixon era but he was never anywhere long enough to do any good (or harm).
Julia Pierson accepted a very challenging job. A change of culture is difficult and usually takes the most time.
It is difficult (but not impossible) to get Governmental action related to meeting “urgent combat needs”. Anything else may (and should?) take a generation or more in which to observe a change.
Would we really want the world to know all the recent failures that have involved the Secret Service?
President Obama, James Clapper, and Susan Rice should resign because of obvious inability to do their respective jobs.