I hear this very often, but the difference with me is that I don't feel very confident in any language. I have a mediocre experience in 4 or 5, but I don't know any one language in serious depth.
You might argue that this doesn't matter, and it's the overall programming mindset that counts. The problem is that the interviewers tend to want me to write the answers to algorithmic problems in a real programming languages, and because I am out of practice, I spend too much time thinking about how to write the language, rather than the problem itself.
I should also add that in the interviews I've had, it's been quite common that interviewers ask quite advanced-knowledge questions about a specific programming language. E.g. I was recently asked by a very well-respected company to explain what a Future was in Java, and I had no idea.
Those are the reasons I think it would be good to really explore a single language.
You might argue that this doesn't matter, and it's the overall programming mindset that counts. The problem is that the interviewers tend to want me to write the answers to algorithmic problems in a real programming languages, and because I am out of practice, I spend too much time thinking about how to write the language, rather than the problem itself.
I should also add that in the interviews I've had, it's been quite common that interviewers ask quite advanced-knowledge questions about a specific programming language. E.g. I was recently asked by a very well-respected company to explain what a Future was in Java, and I had no idea.
Those are the reasons I think it would be good to really explore a single language.