I give stage checks at a part 141 school and can tell you that I usually look at their test scores, but that doesn't drastically change the contents of the oral exam. Typically if you did poorly on your test, you don't know as much as you should. The increased oral time is usually me trying to beat the answer out of a student or give them several hints. I also let students dig themselves quite a nice hole with wrong information. If we are talking about weather patterns and they get something incorrect and then they contradict themselves a few questions later, I will bring that up. They usually end up trying to piece together bits and pieces of information they don't have a good grasp on. 90% of the time that is the reason an oral takes longer with a poorly prepared student. For me at least, they are all expected to know the same amount of information.