There are multiple reasons why analyzing your GraphQL Schema's usage is important, including optimizing APIs to better suit clients' needs, documenting the most used fields, deprecating unused fields, and safely removing deprecated fields without breaking them. To analyze schema usage, you can divide the task into three parts: response type field usage, field arguments usage, and input type field usage. By analyzing these parts, you can gain insights into how your GraphQL Schema is being used and use this information to implement breaking change detection, which involves comparing changes to the Schema or one of your Subgraphs to the last known good version and finding potential breaking changes that would affect clients using specific fields, arguments, or input types.