Notes from the Google Webmaster Hangout on the 6th of March 2018.
Handpicked Reviews/Testimonials Shouldn't Have Aggregate Review Markup
You should only include handpicked reviews from Google+, for example, to add to your site as long as they aren’t marked up. Aggregate review markup should reflect the whole set of reviews.
Sitemap Files Returning 404s Don't Cause Issues for Google
Sitemap files that return 404s don’t cause any issues for Google from an SEO perspective, they will just be left as 404s.
Sitemaps Submitted Through GSC Will be Remembered for Longer
Google’s memory for sitemaps is longer for those submitted through Google Search Console. Sitemaps that are submitted through robots.txt or are pinged anonymously are forgotten once they are removed from the robots.txt, or if they haven’t been pinged for a while.
You Can't Disavow an Entire TLD
There is no way to disavow an entire TLD. John advises against doing this as individual links aren’t reflective of the entire content of a site. Google is also getting better at recognising and ignoring unnatural links itself anyway.
Google Automatically Applies Geotargeting to ccTLDs
Google will automatically apply geotargeting to ccTLDs meaning you will get a slight boost in rankings for searchers in that country.
Differing Mobile-Friendly Tool & Search Results Due to Indexing Delays or Rendering Issues
Differences between the mobile-friendly tool results and search results listed as mobile-friendly are due to sites not having crawled an updated mobile-friendly design, or Google having issues rendering the page due to embedded content blocked by robots.txt, or is hard to fetch.
Google Can Proactively Assume Duplicate Pages Before Crawling Them
Google will sometimes assumes that pages are duplicates before crawling them. This can happen when you have multiple parameters for your URLs that don’t actually change the content being served.
Large Hreflang Sets Should be Included in Sitemap Files
If you have a large set of hreflang tags then John recommends putting these in your sitemap files as this makes them easier to maintain.
Duplicate PDFs Are Seen as Duplicate Content
Duplicate PDFs are seen in the same way as duplicate content. For duplicate PDFs Google would pick one to show in the search results.
Page Layout is Only an SEO Issue for Mobile-Friendly Testing
Page layout is only really an issue for SEO when it comes to mobile-friendly testing and the mobile interstitial update.
Hreflang Isn't Needed for a Language Change
Hreflang is only needed for instances such as using the same language for different countries. It isn’t needed for a site which changes its language completely.