More on 1%ers
I had a friend who did very well at university studying 80% of the course. He looked at previous exams and worked out what was most likely to be in the next exam. A bit part of the reason he did this is because he was working part time and had limited time, so he worked out the odds to become successful within the limitations he had.
Leaving no stone unturned is all very well, but if there are 100 stones, each takes 1 second to turn, and you have to win in 60 seconds, that is not an option.
You have to carefully calculate which ones are most likely to give you success, then do your best with them.