The "new posts have been posted" feature is so you can update your post accordingly if you are having a discussion with someone and they post new information while you are still writing your post.
Any time you "preview" something you are writing, it is saved to drafts, so if you are writing a long post, make a habit of previewing it from time to time.
I just checked my drafts and found those posts which I hadn't previewed earlier but then I saw this message "Drafts are deleted after 7 days." I was trying to search a draft which I had previewed on 16th May but it's already deleted and it was an important code which I lost. Anyways of getting that draft?