A very helpful post... One of the interesting points you make is regarding the changing of a correct answer to a wrong answer at the last minute. I see this happening a lot with students I coach through the PPL exams. They are briefed very carefully that if there are any questions that they're not completely sure in answering, 99% of the time their intuition is usually pretty good at picking the right one (assuming they've done the studying!). Typically however, as they go back through the paper, they start second guessing themselves and inevitably change the answer - only to find later it's now the wrong one. Therefore I always say in the pre-briefing, unless they've made some very obvious error in answering a question (i.e. ticked the wrong box by mistake), leave well alone... The intuition and common sense can be quite powerful allies!