Monorepos, used by major tech companies like Google and Meta, house millions of lines of code in a single repository, facilitating collaboration across vast engineering teams but also presenting challenges related to size and complexity. These companies employ "stacking," a workflow that breaks large changes into smaller, manageable pull requests to maintain productivity by allowing continuous parallel development and avoiding bottlenecks. The integration of specialized tools, such as Google's Bazel and Facebook's Phabricator, optimizes the codebase management and review process, while robust CI/CD workflows ensure seamless integration and delivery of code, minimizing deployment risks. These methodologies, traditionally employed by tech giants, are now accessible to smaller organizations through tools like Graphite, which democratize advanced workflows and enhance developer productivity regardless of team size. This comprehensive approach to software development, integrating monorepos, stacking, and CI/CD, exemplifies best practices for delivering high-quality code efficiently and reliably, offering valuable insights for teams of all scales.