How reliable is the eight-character fortune telling?

Metaphysics, such as five elements and four pillars, Zhouyi, etc. , circulated in China for thousands of years, puzzling. How can a few people be proficient in all technologies? If they are really experts, then their reliability is above 80%. If they meet people who only know fur, they will get into trouble, and even some charlatans can't understand the eight-character god and avoid it. How can they be accurate?