Increase post count to 20 - Right Way

gistfile1.aw

<?php

add_action( 'pre_get_posts', 'be_increase_posts_on_quotes_archive' );
/**
 * Increase posts on Quotes Archive
 * @author Bill Erickson
 * @link http://www.billerickson.net/customize-the-wordpress-query/
 *
 * @param object $query
 */
function be_increase_posts_on_quotes_archive( $query ) {
	if( $query->is_main_query() && $query->is_post_type_archive( 'quotes' ) && !is_admin() )
		$query->set( 'posts_per_page', '20' );
}