I know with celebs, they make sure they get photographed by changing their clothes a lot, or if they don’t want to, they wear the same clothes; ie Madonna in Adidas tracksuits a few years ago, because there is no money for paps if it is the same outfit, as it does not look like a new photo iyswim
Kate’s “aididas tracksuit outfits” are her skinnies and Breton tops.
Her coat dresses are different enough that photos can be differentiated, eg st patrick’s Day 2011,12,13,14,15,16. Same as the cenotaph.
Both Camilla and Kate stick to a palette of pastels, white and cream so they stand out. HM has first dibs on neon and bright colours, and Meghan generally goes for navy, black, beige or blush unless she is on tour.