I'm wondering the same...
I guess the usual for caching: disk space usage, and stale results if the cache key is not good enough (if the length of the docs is any indication, it's probably good enough 🙂https://ccache.dev/manual/4.10.2.html#_how_ccache_works)
I wrote the original integration doc used by reactnative.dev so yeah. However! When we turned on the integrated toggle in react-native-google-mobile-ads repo we had one contributor that didn't have ccache installed in their machine and it didn't handle that, manual integration did...