In the 1940s, women were encouraged to use their hair to ‘fix’ any flaws in their face.
If she had perfect, shiny hair with a good color, she should use it to frame her face. If she had a full face, she should use a 1940s hairstyle that piled hair on top of her head to distract from it. If a thin face was her problem, her hairstyle should be down and over her ears to make it look wider.
All of these suggestions contributed to a variety to hairstyles in 1940s.