Here's the OG tolerance study done on psilocybin and LSD: https://link.springer.com/article/10.1007/BF00407974

We need more studies on the long term effects of heavy psilocybin use. We know how chronic use of alcohol and cannabis affect people fairly well at this point. We also know a lot about regular psilocybin use, but not a whole lot about what happens to people if they take it for 20 years.