For the first ten years of my open source life, I spent tens of thousands of hours pouring over hundreds of thousands of lines of source code across perhaps a dozen or fewer projects, mostly GCC, G++, GDB, and various other parts of the GNU toolchain. If there were a PhD in open source software, I was definitely specialist enough to have earned one. I was vaguely aware of the mountains of source code in the BSD distribution, and obviously Linux, but didn't really pay much attention to that until I joined Red Hat.
For the ten plus years after that, I have barely succeeded in scratching the surface of the 10,000+ packages that can be easily installed without the need to study the source code. It is both a luxury to have available the resources that are represented by the 200+ million lines of source code packaged for a typical Linux distribution, but it is also overwhelming...how can one possibly know all there is to know? And yet, I find that when I need to look for something, it's there. When I needed to control and monitor some PTZ network cameras, I looked for an open source solution and discovered a really wonderful package called Zoneminder.