1. The document discusses using Buck as a build system for an app with multiple developers working on different components across several apps that need to share code. 2. Buck provides advantages over other solutions like Xcode by automatically managing shared modules, caching builds for faster rebuilds, and only rebuilding components that were changed in a pull request. 3. The company iFood migrated from Xcode to Buck and saw build times drop from over 30 minutes to under 10 minutes for pull requests by leveraging Buck's caching and ability to only test the affected parts of the code graph.