I enjoyed playing a few mini challenges of 24 Hrs categories. I was thinking if there should be additional 24 Hrs mini challenge badges for rest of categories.
When you are done with all of 20 categories, you can earn Major Challenge Badge in 24 Hrs. It is similar to All Round Quizzer. I think that is more challenge than All Round Quizzer because you only need 5 quizzes per category comparing to 2000-3000 points for 24 Hrs category.