Again I don't know if they have changed the format since I did mine. But I do recall that four questions could be linked ie: the ground speed from the first question is needed to calculated the time for the following. So one mistake can actually lead to you getting two to 4 more questions wrong.
So I believe you can't really afford to get anything wrong, put it this way if you take 98 % of the exam time to accurately answer 80% of the paper and you then just put guesses for the remaining 20% in the last 2 minutes, in theory by probability you should still get 5% for guessing 20% (1 in 4 correctly guessed).
Small margin for error the 80 % answered accurately then you should still come out with an 80% mark.
That's is my logic. I didn't have to do a single resit. GNAV as said is the only exam which had me working to the last moment.
I also recall that ridiculous accuracy was needed when using the CRP, something you will never use in actual IFR flying. So I always used a 0.5 mm lead engineering pencil with a small tri square to mark and measure the position on the CRP (so better to have one without the wind-arm).