When I worked civil service, I tried to act as an honest broker, to assure that the government got the product it asked for. That required a lot of detailed tests of the product, and review of all the data collected. With a contractor of questionable skills, that was a great deal of work, and resulted in adverse reports causing at least one project to be canceled.
When I worked with a competent and occasionally brilliant contractor the work involved was just as detailed, and the documentation required was just as massive, but less satisfying.
Eventually I went to work for a contractor. I was able to select one that was competent and occasionally brilliant.
I did a lot of work as a sub-contractor on government projects or the Navy, Army, Air Force, GSA, NSF and many I forgot.
On my first project, I bid it just like I would for a private company and lost my ass. The contracting officer was quite arbitrary and waived fire code and generally accepted practices. I had to modify my drawings and add quite a few disclaimers. That was the GSA. I found the Navy work more satisfying though the preliminary designs they furnished were totally impractical and unrealistic. Nonetheless, it took time to show them why and have them agree to revisions.
The bottom line was I estimated my fee the same as for private industry and doubled it to make sure I didn’t lose money on the projects. I was still “competitive.”