McKinsey was doing some work for their dept. I asked him what they did. He said, "McKinsey asked us for lots of information. Then they put it into a dossier and gave it back to us."
Information is siloed, teams compete rather than cooperate, any team's own dossier is going to be seen as biased and unobjective.
There's real value in hiring a neutral, competent vendor to come in, assemble the relevant information using best practices, and present a "dossier" with common-sense conclusions. Then the leader who hired them can use that as political cover for taking the necessary actions they wanted to in the first place, because the leader is no longer siding with one bureaucratic faction against another, but merely taking objective advice from an outsider.
That's actually worth a lot.
Last year, we had 2 consultants hired from some Big 4 consultancy. The manager told us to give them whatever info they need. They came with us on a grand total of 2 calls. The scheduled 3rd call we could not attend coz of overlapping schedules. They never bothered blocking my calendar and I never heard from them again.
I reckon the manager wanted to use them for some political purposes.