Hreflang is Not Required For Untranslated Pages
As hreflang is handled on a per page basis, if you have different language versions of your site but not every page is translated, it isn’t a requirement to have hreflang set up for these pages. John recommends choosing the method that best suits individual websites, this could be either including the URL in the hreflang set or not including the URL.
Hreflang Can be Implemented on Small Groups of Pages
Hreflang doesn’t have to be implemented across an entire site. Sometimes it makes sense to implement hreflang on individual pages or sections where there are problems, or where it is especially important that the correct page is shown.
Only One Version of Same Content On Different Country Sites will be Indexed & Appear in GSC Performance Reports
If you have the same content on multiple language variation sites, Google will pick one to index but will use hreflang attributes to swap out versions of the page based on a user’s location. However, only the page that has been chosen to be indexed, and used as the canonical, will be displayed in the GSC performance report.
Hreflang Can be Implemented on Small Groups of Pages
If you’re only seeing issues with how your homepage is being displayed, then you can add hreflang to that page. You don’t have to implement hreflang across large sections of the site.
Hreflang Not Necessary For Non-Canonical Pages
It isn’t necessary to implement hreflang on the non-canonical version of a page because it won’t be shown in search, therefore any hreflang annotation won’t be used by Google.
Google Can Process Hreflang Tags Regardless of How They’re Implemented
It doesn’t matter to Google whether you implement hreflang tags in the HTML, in the HTTP header, in an XML sitemap or through a combination of these methods. Google will process the information in these tags regardless of the implementation method.
Hreflang Not Needed For All Page Types as Can Add Unnecessary Complexity
Use hreflang for pages which need to be linked between different language and country versions. Hreflang isn’t needed for all page types, like pagination and filtering, as this can add unnecessary complexity.
Use Hreflang & Canonical Tags to Handle Partially Translated Websites
John recommends using canonical tags and hreflang tags to tell Google which language version is preferred if you only have parts of a website that are translated, instead of the entire site.
Hreflang is a Minor Canonicalization Signal
Google uses hreflang as a small signal when picking the canonical version of a page, but this needs to be backed up by consistent signals provided by rel canonicals, internal linking and sitemap files.