Hi Russ,
When you say:** "Google Keyword Planner combines similar words together for volume"**
Is it not perhaps because Google treats similar keywords as one keyword?
Or is it because Google uses LSI to find synonyms of words you want to rank for.
"LSI looks for synonyms related to the title of your page. For example, if the title of your page was “Classic Cars”, the search engine would expect to find words relating to that subject in the content of the page as well, i.e. “collectors”, “automobile”, “Bentley”, “Austin” and “car auctions”."
Taken from: https://www.searchenginejournal.com/what-is-latent-semantic-indexing-seo-defined/21642/
So as you can see, all the words Google groups in keyword planner would be relevant since if I want to rank for "collector's cars" then I would want to know what are all the monthly search volume for the all possible variations of that keyword which I want to rank for.
Am I missing something here?
Would like to know your thoughts.
Thank you in advance.