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In researching the best practice for adding sites to the Search Console, I've often seen it suggested to add separate properties for different versions of the same website. Even in Google's own documentation it states:
"Similarly, if your site has http:// and https:// versions, you should add each as a separate site."
I've seen the same suggested for www/non-www. So if a site is accessible at all the variations of http/s and www/non-www we should have four properties.
But what if the site is only accessible at one variant? i.e. https and www are forced via htaccess, so only https://www.example.com can ever be accessed - should we still add all the variants?
In essence, the problem is that I don't know why Google wants us to do this, so I can't work out if it'll be ok just to have one instance.