Originally Posted by
runner pat
Often the hole is too small to see(especially with aging eyes) and it's faster to replace the tube and use the full sink method at home.
So replace the tube for the first flat and then use the patches if you need to. An easy way to find the hole is to inflate the tube while out of the tire and listen for the air. If it's too loud, then pass the tube by your face (very sensitive skin) to detect the leak.