Stone pounder - GIF

[ibdennyak]

For some perhaps. But hammer is still in her periphery of vision.
Others have a well developed sense of rhythm. Does every drummer watch each action of percussion? Are there pianists, harpsichordists, banjo players that need observe each of two separated hand movements? Granted, the injury potential is nil, but far more complicated.

Most people call it practice or experience. I will say, if it were me, I would have invented some kind of tool to use rather than my hands, but she seems comfortable with it. I always said, the best safety equipment is the thing that keeps your ears separated.