Good post with a lot of deep thoughts.
I personally used to do the self debrief method. by the time you are well into the self debrief the candidate will have realised himself where it is going.
One useful thing I was told and then trained and used on checks, was to stress to trainees that a major cock-up at the early stage of a check may not necessarily be an automatic fail. Allowing it to demoralise and destroy the further operation will (Akin to driving looking out of the rear window!). I stressedt that although the Gold Stars hed been lost, demontrating the ability to recover the situation and get the operation back on track could recover most of them. This would then cause me to review the original `Fail' point and see if it could not be viewed in such a way as to make it a severe debriefing point.
This of course applies in the real world, where a mistake has to be put in the past and moved on from.
Thanks for all the info chaps.