You don't have to jump in at the beginner level if you already have foundational knowledge of a certain subject, and Skillshare makes it easy to start at a level that makes sense for you without having to waste time with content you already know. On the other hand, content is offered for beginners of any subject as well, so it's very adaptable to each situation. Continuing education and training is never a bad thing, so I don't really think there are situations where it's not appropriate to use.