I have to confess something: My dayjob is as a build engineer in a very large C++ project with somewhere north of four million compiles per day. On any given day, I'm picking bits and pieces of the GCC or DistCC codebases out of my beard after work.
I've also been using Gentoo as my daily driver for 19 years. And I only set up CCache for it today. And because I apparently hate myself, I put the cache on a CephFS mount. Let's see how that goes.