Mathematics Advanced is one special case regarding teaching the Preliminary course in Year 10.
In the Year 10 syllabus, there are three option topics which are Circle Geometry, Polynomials, Functions and Logarithms. These concepts are revisited again in the Mathematics course and especially in Mathematics Extension courses. The aim of this is to help students prepare for senior Mathematics, especially for Mathematics Extension 1.
However, these topics are not a requirement of the School Certificate and are "option" topics meaning that it is up to the choice of the teachers, in whether they should teach those topics. Many schools choose to teach these topics after the School Certificate while others may not even touch them.