From what I understand you only get that boost into 'Recent' the first time your game gets published and indexed. The FAQ is a bit vague on the whole process, though. For example I am pretty sure I once got one point in my publishing e-mail stating that pages in prototype/without downloads will not get added into the search results. Which makes sense, but it leaves the question if it still counted as published then or not. So the same could go for some other selectable types or circumstances.
I guess one way of seeing is that if you would know it too exactly it may be abused? And seeing as itch.io clearly states that you should not rely on the recent tab too much anyway to gather a following, I guess it is debatable if such things should be updated into the faq eventually or not.