One does not avoid incompetence if one makes an attempt whose likelihood of success is too low. This seems little more than analytic: when the performance is in a domain that imposes standards of risk, attempts may or may not meet such standards. And the relevant competence of agents then includes reliably enough meeting those standards.

You attain aptness by judging while in good shape and in a good situation (good light, good distance, etc.), through the exercise of good barn-sorting epistemic competence.

A hunter archer can also be out to shock by taking crazy shots. What makes his shots "crazy" is set by excessive risk, judged by hunting-archery standards, which would tend to draw agreement from knowledgeable observers.

It is possible to produce something that is grammatical either by chance or under the supervision of another. To be proficient in grammar, then, one must both produce what is grammatical and produce it grammatically, that is, in accord with knowledge of grammar in oneself.

When we speak of ordinary unqualified knowledge, my thought is that we are implicitly relativizing to the standards imposed by our evolution-derived humanity. These are standards that determine when we consider it appropriate to store beliefs just as a human being, rather than in one's capacity as an expert of one or another sort. Such stored beliefs are to be available for later use in one's own thought or in testimony to others.

There isn't a formal definition of success.

Intuitive seeming is in my view an attraction to assent based on nothing more than understanding of the content that upon consideration attracts one's assent. But such understanding-based attraction can differ dramatically in epistemic quality. Some such attractions represent nothing more than superstition or bias absorbed from the culture, sans ratiocination.