Good question, and thanks for the detail. You can think of a full refresh as just that. It does a full replace of the extract contents based on the underlying database that it connects to + any extract filters. Internally, I believe that it creates a new tde extract file and then once it's done populating, then it overlays the existing tde or repoints the workbook connection to the new tde.
Thank you for the quick answer. Just to confirm and clarify, there is not a way currently in Tableau where I can say "only do the full refresh for 1 week behind?"
There is no native way. There is a hacky workaround that I call "back dated incremental", but it's high in effort, is somewhat manual and in order to get rid of the manual nature of it, requires lots of scripting. See this post if interested. Refreshing Large Extracts Faster