The shots have been deliberately taken in harsh light to bring out the different facets of the various angles of light onto the face. Each of these positions work in the full range of light/shadow intensities. What you see here is the very basic lighting positions for the face, this is just the beginning of understanding portrait light.
Making a portrait is about bringing out the individual who is your subject through the image. So, it is up to you to get the light and position right for your sitter. This is a demonstration of the technique, not the definitive photograph for these shots.
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Thank you for posting this and the explanatory notes; great food for thought.