I think you either are lucky or not working on some low level problems. I had at least two cases (in last 5 years) where I had to debug code and enter Windows libraries reading assembler code using cdb/windbg. It was painful knowing that in Linux I could simply read code, understand it and potentially fix it. In some cases low level tools help avoid debugging assembler (like dependency viewer, process monitor, spyxx, wireshark and etc.).

It is really not about fixing something but understanding what behavior underlying libraries expect from software you are writing. The situations where documentation is technically correct but practically useless.