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
Don’t Change URLs and Domains at the Same Time
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.