The cited pigment and sunlight studies are published evidence. The following is Alex's craft approach after 16 years of tattooing: design the piece for its real physical size and placement, preserve a readable range from dark to open skin, and avoid relying on tiny value differences to carry every important feature.
Black-and-grey realism creates form through light and shadow. Portraits, animals, horror, surreal imagery, and micro realism can all use that language, but they do not need the same scale. A forearm panel, wrapping sleeve, hand, rib, and back piece provide different space and viewing distance. The tattoo process explains why placement and scale are resolved before drawing.
Look at finished work, not an abstract longevity score. Alex's black-and-grey portfolio shows how value and composition change across subjects. The style comparison explains how this differs from traditional, neo-traditional, and cyberpunk anime without declaring a universal winner.