Redundant courtesy accidentals are clutter, not caution

Restating an accidental on every recurrence of an already-governed pitch, or adding courtesy marks at every octave/voice boundary regardless of context, is over-notation and should be removed.

Gould gives explicit guidance against over-cautious restatement; Ross likewise treats excessive courtesy marks as amateur engraving. Universal agreement clutter is the opposite failure mode from omission.

This rule can be decided from pitches, durations and voices — no layout required. A validator can check it before anything is drawn.