I have found that for most categories, it takes 3 quizzes to generate a subcategory... But, typically, this is in a much higher up folder (such as "A" authors in "Literature"), one not already super deep in the depths of sub-folders. World-Government-Australian Government is already fairly far down in the subcategories, so it will likely not get any new folders within for at least a while.
"The only water in the forest is the River."
Editor: Video Games, Entertainment