This is an excellent statement emphasizing the importance of concepts like deliberate practice and a varied curriculum/experiences. I think this idea applies to all learning.
In reality I think most developers have careers that look like:
* 2-3 years of explosive growth and exposure * 5-10 years of slower growth and increased mastery * then diverge to shorter periods of stair-stepping (new technologies / faster mastery), coast on what they already know well or move out of active development
> Practice makes permanent. Perfect practice makes perfect.
Of course "perfect practice" is an ideal, and you can't achieve it yourself without having someone or something assist to evaluate in most cases. But repeating the same mistakes for 1500 hours just makes you really good at making those mistakes.