I've always made a point, that when I seem to hit my cap on something, instead of moving up go sideways. For example, if you are a rock guitarist and seem to be showing little progress, perhaps instead of continuing trying to progress in rock, venture into playing in a jazz styling. Oftentimes, I find this will help me progress further than I would have otherwise. And it can also allow some inspiration, dabbling in styles you are as knowledgeable about.


Cheers,
Deryk