This is an interesting tangent, because unlike musical ability, or obviously, athletic ability, writing is independent of ones physical skill. So I would look

This is an interesting tangent, because unlike musical ability, or obviously, athletic ability, writing is independent of ones physical skill. So I would look to other skills of the mind to find the answer. A comment here once told of how the commenter's father had been working on a physics phd, he worked hard, got a nice letter of recommendation. But when he asked to see a friends letter there was little more than the line 'Nobel material'. After that he quit for a different path. I expect there is a point where diminishing returns become greater than the cost of effort. You may be able to improve yet, but it may not be worth it.