What: Holding the narrative lens steady (first, or close-third) without head-hopping between characters' minds.
Why: Head-hopping confuses the reader and breaks immersion; steadiness builds trust and depth.
How: Choose one lens for the scene and write only what that character sees and knows.
Common mistake: Suddenly shifting into another character's thoughts in the same paragraph.
Exercise: Write a scene between two characters from one lens only, never revealing the other's thoughts.