There isn't a formal definition of success.

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.

Flourishing is properly the main human end, and flourishing is activity of soul that succeeds in accord with virtue.

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.

If we have a better understanding of knowledge than we do of such justification or competence, then we can explain the latter through the former.

In order to qualify as a judgment, an affirmation must aim at getting it right aptly, through competence, and not just through a lucky guess.

Normal adults can doodle, amble, and drift with no need to assess risk, since there is normally no risk at all. Jazz improvisation seems less subject to standards of risk than surgery, and less than much formal athletic performance, as in a tennis match.