Too Much Expertise Can Be Detrimental to Creative Greatness

The deliberate practice approach assumes that performance is a linear function of practice. While this may be true for many well-defined domains of human achievement, this doesn't appear to be the case for creativity. The relationship between knowledge and creativity is best characterized by an “inverted U-shaped” curve: Some knowledge is good, but too much knowledge can impair flexibility. 

In fact, in some fields such as creative writing, there is an optimal amount of formal schooling, after which further schooling decreases the likelihood of writing highly creative fiction.