The people who draw are aware of the problem of drawing a large area, like the Jemaa el Fna square, filled with all kind of people, and in the darkness of night.
Whenever there is too much information, like in the streets of the Medina, where there are crowds on bikes, donkeys and carts, and where shops sell all kinds of items, we must decide what we wish to convey.
A good solution may often be to sit in a secluded corner, and sketch some of the passers-by.