Use Adsense In-article ad within pages content

I am trying to find an implementation that will allow posting an Adsense in-article ad every 12 paragraphs within the main content area of my Pages.

I found one guide that suggests using this code in the functions.php

add_filter( 'the_content', 'prefix_insert_post_ads' );
function prefix_insert_post_ads( $content ) {
$ad_code = ' Paste your AdSense Code Inside this quote';
if ( is_single() && ! is_admin() ) {
return prefix_insert_after_paragraph( $ad_code, 12, $content );
}
return $content;
}
// Parent Function that makes the magic happen
function prefix_insert_after_paragraph( $insertion, $paragraph_id, $content ) {
$closing_p = '</p>';
$paragraphs = explode( $closing_p, $content );
foreach ($paragraphs as $index => $paragraph) {
if ( trim( $paragraph ) ) {
$paragraphs[$index] .= $closing_p;
}
if ( $paragraph_id == $index + 1 ) {
$paragraphs[$index] .= $insertion;
}
}
return implode( '', $paragraphs );
}

1. Will this also work if I just use this code as a Hook for all pages and enable the "Execute PHP" checkbox?
2. Any other ways to automate publishing ads within the content?