It is tempting that putting some paragraphs to the tutorial when you think "this should be documented!" but there is no good place in the library reference.

HOWTOs is the document for advanced topics.  But it doesn't cover wide area yet.  There is no topic about module search path or site-packages.

Since the tutorial covers a wide area, including module, it is very tempting to add many random notes about module.

But please remember that the primary reader is people new to Python.  (I learned Python 2.4 by the tutorial!)

The reader has learned Python syntax and basic types in chapters 1~5 and now learning how to split a Python program into multiple files.

So please don't try to answer the question in Stackoverflow in the tutorial, unless it is worth enough for the reader.