Regarding "(all content)" Sections

I have a few questions regarding how content is organized, notably regarding the "all content" math sections. using the API, I made a list of every topic in the topic tree and associated each one with a list of every section where it shows up.

• Doing a search for "(all content)" revealed large amounts of content not associated with the "all content" topic it should be. For example, "Comparing areas and perimeters of rectangles" is not available in "Geometry (all content)". If this section covers "all content", then how come some content is missing?

• There are no "Calculus (all content)" or "Statistics & Probability (all content)" sections available. Should these be available like the "all content" missions for Arithmetic, Geometry, and Algebra?

• Some pieces of content show up in as many as 15 places or more, yet appear to be linked through the website. Could the topic tree be reorganized to separate content from where it shows up such as to reduce the amount of duplicate data?

• If exercises fall under multiple sections, then what decides which one is directed to by search? Should search always direct users to the "all content" section for that topic?

Thanks :)