I once had the pleasure of haveing a National Champion crew for me. He spent very little time looking at my sails, which were older than most of the others out there. He almost NEVER took his eyes off the water and wind ahead of us and had me tacking about twice as much as I normally would on a lake in shifty wind. Thanks to me, we got 3 bad starts but he turned that into 3 first place finishes, all because he was wathcing the wind, called the shifts correctly and worried very little about sail trim. THAT is why those guys don't use telltales. If you never look at them anyway, why put all that drag on your sail? (Me? I need them!)