Many years ago I attended a presentation by a guy who wrote on the
psychology of computer programming. He put a picture up on the screen
and asked people to find all the defects. There was a wide range of
numbers from people in the audience but nobody found them all.

The reason I bring this up is I have a problem with noticing torn
endgrain on bowls at least until after I put some finish on when all
the defects often appear out of the blue. Do the experts in this group
use teir fingers to find defects, expert vision or some other magic
techniques? Thanks for the ideas.