What is the best format for Canonical URL?

Hey guys
I have a question about the canonical URL in WP.
I use this format: MYDOMAIN.COM/PRIMARYCATEGORY/POSTOFTHEDAY for this use Yoast. In fact it's the only reason why I still use that plugin because I'm thinking about moving to All In One SEO (it weighs less and it's faster). But I would like to know what you think of my Canonica URL builder, is it okay as it is? Or should it only be MY DOMAIN.COM/POSTOFTHEDAY as it is traditionally done
I clarify that my website is an adult content page.
Thks!

Canonicals should be pointed directly to your site post's URL - if the site URL is already mydomain.com/thisismysitesposturl , then that should be your canonical link for that page.
It doesn't make sense to point your canonical to another url, unless if you have keyword cannibalization issue, or if you want to redirect search engines to index/list the right link for a particular web page on your site.
Or most importantly, if your site is https, then the canonical should be pointing to your https: url and not http.