Too much color
In the days of film, we used saturated films like Fuji Velvia for landscapes but less saturated films for portraits. No one wants their face to go nuclear. If magenta is getting towards 50%, beware of the well-done look.
The surprising power of cyan
On pleasing photos, cyan usually falls between 30% to 50% of the magenta value. Less than 30% of magenta makes sunburn; more than 50% of magenta makes makes them ghostly blue.
These three photos have the same yellow and magenta values; only cyan changes. Cyan is 24% of magenta on the left (slightly low), 40% in the center, and 60% on the right (too high).
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