Diagnose before cutting
A dark area may be a guideline, excess weight, dense growth or a shadow created by head shape. Brush the hair, change the viewing angle and compare nearby sections before selecting a shorter setting.
Target only the problem area
Use the corner of the blade or another narrow cutting surface where appropriate. Broad passes can remove the surrounding gradient and replace one line with a larger light patch.
Work through the transition
If the band occupies more than one length, move through adjacent settings rather than expecting one guard to solve the entire area. Keep each adjustment small and check the effect before continuing.
Know when to stop
Not every variation can or should be erased. Chasing natural density may compromise the silhouette. The goal is a balanced visual transition, not uniform exposure under every lighting condition.