Spotify mostly uses independent repos for all code, but some configurations (e.g., DNS) are contained within a single repo. Some big companies do successfully

Spotify mostly uses independent repos for all code, but some configurations (e.g., DNS) are contained within a single repo. Some big companies do successfully use Git for monorepos though (e.g., Microsoft – search for "GVFS"). Note: I haven't been there for two years so of course some things may have changed.