Learning curve for the musician

This afternoon, I've realised this. I'm sure, there are quite a lot people who won't agree with me, but that's so from my point of view, at least until now.

In the musician life, there are some differences during the learning process, It isn't always possible to learn by the same way or with the same speed.

The explanation is almost unnecessary: When you start, it's easy to improve, but while your knowledge increase, it's being more difficult to learn the next lesson, to go up another step.

I don't think this is bad, although it'd be better if the progression was regular, simply, it's so.