I am fortunate to get to read almost all of these before creating the cover art - notable exceptions are magazine covers like The Drabbler, Cover of Darkness and Sounds of the Night.
Many depict actual scenes from the text, like Serpent Singer, Cloudburst, and Walking Like Morpheus. Some are just general depictions of the subject, like Fresh Blood, Bedtime Stories for the Apocalypse and The Drabbler Special Edition. A few are character depictions of a possible moment in the text such as Ascendant, Charlotte Cauldron and Death Metal.