David Shrigley makes lists of phrases (e.g., “man being mauled by a lion”), and then he draws 30–40 of them per day. Sometimes he’ll change the phrase (e.g., “man being mauled by a horse”). Each drawing is different, and he only does each drawing once. He discards the majority of them, by his estimate it’s 75%. 

(If he works 6 days per week, doing 30 drawings per day, that’s 9,360 drawings. Quantity leads to quality.)