Notes from the Google Webmaster Hangouts on the 2nd of December, 2016.
Orphaned Pages may be Noindexed
Orphaned pages will be re-crawled, taking up some crawl budget, usually remain indexed, and can still show up in search results but as there are no internal links then they will be considered unimportant and they might eventually fall out of the index.
Identical Synonyms Rank Equally
Identical synonyms are given the same weight, although there are types of synonyms which are not considered identical. E.g. Plurals and variations are likely to be the same, whereas some synonyms are used differently in search.
Use Sitemap Index Count to Measure Indexing
Site: is not an accurate measure of indexed pages, and could be off by ‘orders of magnitude’. The Sitemap Index count in Search Console is accurate for the specific URLs submitted.
Don't Change URLs and Domains at the Same Time
Dont’t change URL paths when changing domains or protocol, as it makes it harder for Google to process the change.
Use Noindex or Unavailable After for Past Events
For managing event pages after an event has occurred, add a noindex after the event, or add an unavailable-after meta tag before the expiry which can help Google stop showing the pages.