Originally Posted by DaveYoung

I think I understand what you are getting at, and that is "don't ask questions that you really ought to know by the time of your practical." I agree with that, but I think tapping into the examiner's knowledge is always a good thing during a checkride. I have learned more during my oral exams than many ground sessions. So, make sure you know your stuff, but don't be afraid to be curious about other things.