My shodan test was about 30 - 40 minutes. However, it took place at the end of a course, and all my technique during the course, as well as my general attitude, were being watched.
I knew some of what would come in the grading, but could have been asked anything. I remember defence against kicks, bokken, knife (real, not wooden), randori, kokyu, showing a jo kata.
I don't really remember all of it.
We are a smallish organisation, and we are required to attend courses to be able to grade, so the senseis are fairly sure who they want to grade by the time it comes to it. Sometimes people make mistakes, which are pointed out, but are told they are overall good enough.
Yours in budo,