Once you know C++ and spends a couple of years of programming in C++, you started to feel that you know the basics and have good command over C++ programming. At this time, the programmer goes to two paths, one who chose to do just fire-fighting and daily work and never upgraded or forced to learn new or more by reading books, participating in forums, and giving presentations. The other group of programmers explores new books to learn C++ in detail and after reading a couple of books on this list, they also realize how much of C++ they know is incomplete and incorrect. That's why I recommend experienced C++ developers to read books to complete the journey from a junior developer to a senior developer.