I've always gone from entry point of the code (with a lot of assumptions) and then do a deep dive of one of the module or branches. After a while you develop an

I've always gone from entry point of the code (with a lot of assumptions) and then do a deep dive of one of the module or branches. After a while you develop an intuition where code may be (or follow the import/include statement). I've explored code like FreeBSD, Busybox, Laravel, Gnome, Blender,... and it's quite easy to find you way around.