Sorry for re-opening this issue but I’m trying to understand something.
The easiest way to control the number of Headlines is to create a category ‘Headlines’ as you mentioned. Now, by removing (an old one) and adding (a new one) you have full control of the Headline size so we avoid the overlapping.
Meanwhile if a plug-in like Sitemap generator is used, will create a hyperlink containing the category (Headlines) and the Title of the post and eventually indexed by the search engines.
If I will remove the post at a later date to make space for a new one, am I risking to end up with a lot of broken links or “not found” at a later date under the Headlines Category?