Drawing frills can be a bit of a nightmare. It takes a lot of effort to get the feel of the fabric just right and adding shadows to each layer is time-consuming. So when an illustration contains a lot of frills on pixiv, it often gets tagged with フリル地獄 (furiru jigoku, translated as “frill hell” on pixiv).
Take a look at the illustrations below to get an idea of how to handle frills. Satono Diamond (from Uma Musume Pretty Derby) certainly looks adorable with her oversized sleeves~!