A schema is only useful if it actually catches bad payloads before they reach your handler. Most teams write the schema, then forget it during local development, or only enforce it in CI on a handful of fixtures. That gap is where the 2 a.
Source: [Dev.to](https://dev.to/lizely/validating-json-payloads-against-a-schema-before-they-hit-your-service-1d39)