Reading this really reminded me of my time as an intern. I think I spent about 90% of my time reading source code then and doing exactly what what's described in this article. A lot of developer time is wasted reading existing source code and I think one problem is the lack of the right tools.
That's why I started building Coati, an interactive source explorer for C/C++. Coati allows you to see the relationships of classes and functions and thereby makes it easier to get an overview of your codebase. This makes the familiarization step of the process much easier.