I see a lot of articles with lots of images found by MyCurator. Are all of those images stored in my Media Library? The quick answer is no, only one image per article is initially stored by MyCurator.
Whether you choose to save the first image as a Featured image or to insert it into the post, MyCurator will store just the first good image it finds into the media library. When you review the article in the Training Posts using the pop-up window you may see a lot more images in the article. Similarly when in the editor after making a post live, you may see a lot of images in the Saved Page meta box.
These other images in the article are NOT saved in your media library. A link to the article is used to get and show the image whenever you view the full article text.
If you then choose to insert one of these other images into your post, then it too will be placed into the media library. So you can end up with more than one image in the media library for a curated article if you insert them into the post.
What about all of those training posts that you never use, are their articles still stored in the media library? No, as training posts are deleted, their images stored in the media library are also deleted. As you may have noticed, old training posts are deleted every seven days by default. You can change the number of days in the Options menu item Admin tab, “Keep Training Posts for how many days?”.
If you manually trash training posts, the images are not deleted until the trashed items are permanently deleted. WordPress does this every week or so, so you don’t have to worry about going to the trash and deleting items after you’ve trashed them.
This also holds true for any posts you may have in draft or published with images. If you delete the post, the images will also be deleted.