Well, I think in most cases this is not about expecting too much. This is rather meant to see how the candidate behave in stressful situation. In other words - there is no expectation that candidate will fly perfectly but rather to see how he manages such sensory and mental overload.
There is a post about Ryanair thread for example where some candidate laments that he did everything perfectly yet RYR told him he failed.
So maybe his approach to problem solving was different than what RYR expected?
On the other hand I have see a post on, I believe, Emirates sim test. Somebody told that he was convinced he failed because he made several mistakes but they told him heh did fine.
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