The Newspaper SP's README is completely wrong about how deleting a newspaper works. It shows a large diagram with the following text:
"Deleting a newspaper object directly (Manage > Properties > Delete Newspaper) will delete all its child Issue objects, and their associated Page objects. "
The chart and text are incorrect. What actually happens is that only the Newspaper object itself is deleted. The child Issue objects remain in the repository as orphans, and will continue taking up space.
If those child Issue objects are deleted, then their child Page objects will be orphans and also need to be cleaned up.
Long-term, we need to fix deleting so that children are actually removed as expected. (With a check for secondary parent objects first, of course.)
Short-term, the documentation needs to reflect reality.