Vincent Dubroeucq

Visit your blog posts listing page, or a single post page, and open up the WordPress customizer.
Under Tiny Thumbnail Settings, choose or upload your default image. That’s it !
Enjoy !

Tiny Default Thumbnail

Allows you to add a default featured image to posts. Just add a default image in your customizer settings !

Grant Mangham

Unfeature simply associates a checkbox with the featured image of a specific post, allowing you to control whether or not this image will show on the single template.

Unfeature

Simply associates a checkbox with the featured image, allowing it to be skipped on single posts.

Tiny Default Thumbnail vs Unfeature