I don't think mastery is a bit. It is much more an analog signal that requires exponential energy input as you move from the initial state to the maxed out stat

I don't think mastery is a bit. It is much more an analog signal that requires exponential energy input as you move from the initial state to the maxed out state. As a result, even though I've done Java and Python stuff for 10+ years, I still wouldn't rank myself more than a six or seven out of 10 on them. I've used JavaScript since very soon after it was released, but I would still only five myself a four or five on it. I don't learn much about programming from Python but am very efficient. JavaScript is still teaching me new things (projects like node.js have helped!). For me, the more interesting question is: what am I learning from this language. This tends to follow the inverse curve: I learn a lot early on, but a language's impact on my programming reduces over time. Learning a new paradigm obviously increases that much more that learning a fifth variant on a paradigm I've used for umpteen years. Of course, different people have different motives. Some may want to be the best 3D programmer out there. That path looks different than my "I want to be an incredibly valuable, generalist programmer". My path let's me work on lots of different types of projects, but I'll never understand AI like Peter Norvig. In the end, look at your real goals, keep track of your progress, and adjust course as necessary to keep moving in the direction you want.