Judgement calls are always a difficult thing to make. 99 times out of 100 you can make then *right* decision, but, that one case *where* someone may not have followed proper procedure ...
Remember, the process of building/repairing a space shuttle is a labor-intensive process involving a ton of specialists and materials ... any one of which failing to live up to their commitments can cause a whole program (like the shuttle) to go down ...
It ain't just 'the guys at the top'. There is a lot of involvement at *all* levels.