Tom McFarlin

Find Missing More Tags scans your posts and identifies which ones are missing the <code></code> tag. This helps ensure consistent formatting across your blog, where the more tag controls how much content appears in archive pages and feeds.
Features:
<ul>
<li>Scans all posts (published, draft, pending, scheduled, private)</li>
<li>Works with both Classic Editor and Block Editor more tags</li>
<li>Clean, modern admin interface with card-based design</li>
<li>Three organized tabs: missing, has tag, and ignored</li>
<li>Ignore posts that intentionally skip the more tag</li>
<li>Quick edit links that open in a new tab</li>
<li>Paginated results for sites with many posts</li>
<li>No settings required – smart defaults work out of the box</li>
</ul>
Why use the more tag?
The more tag (<code></code>) creates a clean break in your content, showing only an excerpt on archive pages with a “Read More” link. Without it, your archive pages might show full posts or rely on automatic excerpts that can cut off mid-sentence.

Find Missing More Tags

Helps content editors identify posts missing the more tag, making it easy to find and edit them.

One Crayon

If a post is saved with a <code></code> tag that is immediately followed by a common block-level element (like a header, div, paragraph, list, and so forth), then two linebreaks will be placed after the more tag to ensure that the block-level element is not automatically wrapped in paragraph tags by WordPress’ content parser.
There is absolutely no reason to install this plugin unless you are using an external editor and having your whitespace stripped out when you save your posts. If you are editing through the WordPress admin screen, then this plugin will be worthless because you can easily control where the <code></code> tag falls by hand.

Breathable More Tag

Ensure that the  tag has space to breathe if the following tag is block-level

Find Missing More Tags vs Breathable More Tag