Custom Posts Per Page provides a settings page in your WordPress admin that allows you to specify how many posts are displayed for different views.
Custom Posts Per Page allows you to specify how many posts are displayed per page depending on your current view. Once settings are changed, the Blog pages show at most setting in the Reading menu will be ignored.
Settings are available for:
Each of the above settings can have a different value for the first page displayed and subsequent paged views.
Custom Posts Per Page makes it easy to manage exactly how your content is displayed to your readers, especially when different views have different layouts, rather than relying on the single setting in the Reading menu or having to hard code options in your custom theme.