The reason behind the lack of study guides for university mainly relates to the diversity of uni. There are so many different courses and units which require vastly different approaches, which kind of makes a detailed guide unfeasible. For example, even in my Commerce degree, what you needed to do varied greatly depending on the unit and lecturer. The strategy needed to do well in one unit was sometimes completely different to what you needed to do in another. Given this, the best we can do is a very general guide like the one we currently have. In contrast, with HS, everyone does the same basic subjects and there are rigid standards - so it's much easier to create guides for each subject.