Some view a forest as a lot of individual trees. Others think that increasing the quantity of trees changes the quality of their appearance as well.
It's kind of like boiling water. You increase the temperature of water one degree at a time, until suddenly it changes from a liquid to a gas. Quantitative change turns into a qualitative change.
When artists draw a crowd, some choose to draw a lot of individuals:
Others don't draw every individual--but they like to imply every individual. Here, Frazetta puts a few representative figures out front, then uses stray arms and legs to suggest the balance of the crowd:
Here, Noel Sickles uses highlighting to carve individuals from the dark masses of crowd on either side of this painting. He is such a brilliant draftsman, he did not compromise on the individual characters the way Frazetta did, nor did he overwork the picture the way that maniac in the Renault ad (above) did.
Then all the way over on the "forest" side of the spectrum we have this lovely painting by Bernie Fuchs. He didn't even try to capture the individual personalities within the crowd.
He viewed the aesthetics of a crowd as totally different from a collection of individuals.
There's a point at which a bouquet of flowers is so large, it becomes a garden. Some artists persist in seeing the individual flower petals. Some create the illusion of painting every petal, using time saving techniques. Others step back and say, "my subject has now changed, from flowers to a garden."