I generally visit all my cache sites at least three times, and for the multis or puzzles I like to visit the cache as if I had never been, entering the coords in by hand and proceeding to the next stage. If it's an area with tough reception, I go more times. I bet I averaged battleship 30 or more times over a couple weeks before I was confident the coords were acceptable.

I think many people figure the averaging feature of GPSrs will give you a decent coordinate, and 95% of the time it probably will. I'm still a proponent of going back another day at least once to make sure. Double checking the posted coords helps tons too. Looking on Google Earth or Maps is a great idea as well.

That being said, everyone makes mistakes, My last hide I reversed my entire puzzle stages so the posted coords were of the actual final. It was actually funny getting a call from the first finder as he was unsuccessfully looking for the first stage (micro) while pretty much standing on top of the final (Ammo box).