They arent especially geared towards realism, but most of the images found on my website pages of illustrations for GILGAMESH (http://www.joey-aristophanes.com/gilgamesh.html) had anywhere between 12 and 18 layers each. The exception was the Flood image, which only (only?) had 10. And all this doesnt include channel work as well, but not many people use channels that much anymore.

Just an FYI as to what can be done in post-op.

docandraider.com -- the collected cartoons of Doc and Raider