As a precalculus student in summer school, I can tell you that a precalculus course takes most of algebra 2, analytic geometry, trigonometry, vectors, matrix algebra and other topics and tries to fit it all into one semester.
I prefer to study each topic individually. Of course, I do not have this choice. Our professor fully understands that not all the topics mentioned above will be taught, especially in the short summer course.
Again, it is a course that covers a lot of the math that you should be familiar with before going into calculus 1 or so I've been told.