Umut I understand the want to be accurate. I'm not suggesting you lower your standards.
What I'm suggesting is that rules like "sunny 16" and exposure tables like those that used to come with every roll of film and the ultimate exposure computer are very accurate, every bit as accurate as a meter. Accurate enough even for working with slide film.
Tables and meters both require building a bit of experience so that you can understand what they are telling you and how to translate that to camera settings.
Neither intrinsically eliminate exposure errors.