Off the top of my head the space shuttle firmware was written by a team that adherred to a very systemic process to ensure it met the spec/reduce the number of bugs, it was often cited in old software engineering papers/books in the time period as the best organization in the world, IIRC in terms of software engineering measurements like defects per lines of code. It would be important to know if someone came from that at the beginning of the space shuttle program when they were creating the standards for work, starting out or if they came on later after the process had been perfected.

I worked in a different contractor in NASA/Clear Lake at the time but even before I read those papers the organization responsible for the shuttle firmware was held in the highest regard.