File structure

WMP is not critical about file structure.
If you drag a directory tree into your music folder it will simply scan all the (sub) directories for music.

By default WMP use a structure

• Root
  • Artist
    • Album1
      • Song1
      • Song2
    • Album2
      • Song1
      • Song2
      • etc

Add To Library

This adds folders to you library.

All folders are monitored actively. If you add file to any monitored folder it will appear sooner or later (most of the time) in the library.

Drag/drop

Another way to add files is to select them in Explorer and drop them in WMP on the library.

If you use Explorer to move file out of a monitored folder and WMP is active, it will notice and keeps pointing to this files.

Options

You can control whether all files should be arranged in this way and what file name convention should be used.

Rename music files… renames the files using the content of the tags.

In Rip Music settings you specify the tags and the sequence to be used.

Rearrange music in rip music folder, using rip music settings rearrange the files using the default directory structure (Artist / Album).

Using these options you have a consistent file structure and naming convention for your files. But every time you change the appropriate tag, it will have its effect on directory structure and/or file name. Something to keep in mind when making a backup.

Sometimes the rearranging is incomplete, part of the files are moved to the new directory, others remain in place.

It might take some time before you see this changes in the directory structure.

Using Apply Changes might help.