From Monorepo — the Google way to do CI/CD:

Source control done the Google way is simple. Instead of creating separate repositories for new projects, they create new top-level folders in their monorepo. This way they keep all the dependencies, variables and code components in one place. This is the reason behind their multiple daily product updates — every code commit essentially becomes a release once it passes the tests!

Can someone who works at Google (or who knows someone that does) attest whether this is true or not?