I agree that simply "counting" is a useless metric. I believe what's useful is exposure to different ways of thinking about programming and problem solving. In my personal experience, exposure to imperative, functional, logic, actor, and meta-programming have all enabled me to learn more about problem solving and to think about programming at a higher level. Can you gain exposure to all of those concepts, and more, in just 3 or 4 languages? Absolutely. Does the potential for learning and growing as a programmer end there? I'd hope not!

As a related note, learning new syntax is by far the least useful aspect of learning a new language. Coincidentally, it's also the easiest element to pick up and takes little time at all. Incorporating new paradigms into your way of thinking takes far longer.