Crashem,
I think what raabid was talking about was fine adjustments to the CG for better flight performance. The manual or plans aren't written by any diety, they aren't always the "best" location, and frequently they are conservitively nose heavy to make sure the first flight isn't a very short one. So one starts with what the instrutions say, and go from there when trimming a plane. Not checking it at all on the ground before the first flight is crazy, which, I think is your point, and I don't think anyone would disagree with it.

The "best" location for the CG can only be determined by flight testing. However, the plans or instructions are usually more than good enough for a trainer and most sport flyers.