Jabawack

Simple Custom Posts per Page (SCPP) allows to configure the number of posts displayed for every custom post registered in WordPress.
See <a href="https://wordpress.org/extend/plugins/simple-custom-posts-per-page/screenshots/" rel="ugc">Screenshots</a> to known why it is called “Simple”.
In your Readme page in Setting tab of WordPress, it adds an option for every post type.
Disable Plugin in Template: 
You can disable plugin filters in your template whenever you want. Maybe you need a query with a different number of custom posts per page for a specific post type. 
Using this code before your query, the filter plugin will be disabled for a specific post type:
<pre><code><?php $GLOBALS['ado_cspp_disable']="YOUR_TYPE"; ?>
</code></pre>
With this code, you can use your personalized query for your loop.
More: 
You can find more informations in the official <a href="http://www.adostudio.it/blog/simple-custom-posts-per-page-397/" rel="nofollow ugc">Post</a> on my Blog.

Simple Custom Posts per Page

This plugin allows to configure the number of posts displayed for every custom post registered.

Scott Reilly

NOTE: This plugin is no longer necessary as of WordPress 2.8 as this functionality is now built-in under the “Screen Options” slide-down menu.
Control the number of posts per page, pages per page, and comments per page that appear in the admin listings of posts, pages, and comments.
By default, WordPress lists only 15 posts in the admin listing of posts and 20 for pages and comments. There is no built-in way to change how many posts/pages/comments to list. This makes paging through the post/page/comment listings very cumbersome, and limits the number of posts/pages/comments you can see at any one time. This plugin provides a dropdown selection field allowing a choice of 5, 15, 20, 25, 50, 100, or 250 per page limits. Each section (post, page, comments) has its own limit separate from the others, and the limits are considered a user preference and not a global setting (so each admin/author can set the limits to their liking without affecting other admins/authors).

Admin Per Page Limits

Control the number of posts per page, pages per page, and comments per page that appear in the admin listings of posts, pages, and comments.

Simple Custom Posts per Page vs Admin Per Page Limits