And also, Python, Riak, Redis. And these are only the tools that I did use with great success.
Others are PHP, MySQL (and other *SQL), Java, C#. Of course, once I found out that they are "no good" for finding new exciting problems to solve, I dropped them, so I didn't become a "master" of them. With the exception of MySQL, which I think I am a "master" of.
EDIT: also, I never claimed that 3 months is the magic number. It was a (wild) guess by someone else.
Second Edit: Also, for quite some time I have been studying C, Haskell, Lisp and to lesser extend some other stuff. I am already quite familiar with the type of problems they shine at. Once such a problem emerges, I will readily jump on it, and will intensify my learning of the tool in question.
EDIT: also, I never claimed that 3 months is the magic number. It was a (wild) guess by someone else.
Second Edit: Also, for quite some time I have been studying C, Haskell, Lisp and to lesser extend some other stuff. I am already quite familiar with the type of problems they shine at. Once such a problem emerges, I will readily jump on it, and will intensify my learning of the tool in question.