wp_list_pages bug in “number” parameter

You can hook into the edit_posts_per_page filter that fires in WP_List_pages right before the pagination is determined.

add_action( 'edit_posts_per_page, 'limit_list_pages' );

function limit_list_pages() {
        $post_type="post";
        $edit_per_page="edit_" . $post_type . '_per_page';
        $per_page=(int)get_user_option( $edit_per_page );
        if ( empty( $per_page ) || $per_page < 1 )
            $per_page=10; //<--- Change this to your new per page number

        return $per_page;
    }