I'm still young, my father not the Leopold Mozart type, so it's too soon to write a personal essay on "what mastery means" that I could take seriously. Perhaps a comment, then.

The process you describe—the deliberate, neurotic synthesis of details and their purpose—feels to me like the parable of the blind monks and the elephant. We walk around our craft, palpating an unruly amount of details, hearing others shout conclusions that make no sense to us.

Mastery, then, would be the moment we learn to see, click our tongues and go, "But of course. It was that all along."