Reddit mentions of The Fire Within: An Elemental Warrior Series (Elemental Academy Book 1)

You must have a super strict definition of what you consider "progression fantasy" (vs I guess other fantasy that doesn't have strict RPG quantification).

Some other series that I consider progression fantasy and I enjoyed:

• Into the Labyrinth by John Bierce (two sequels are out, although these books tends to be on the shorter side). Like, this book is shockingly short. If I hadn't checked the length after, I would have sworn this was at least twice its 178 pages (which is probably good if the author is crazy like me and considers crazy stretch goals like "adapt this into a feature length film").
  
  
• Sufficiently Advanced Magic by Andrew Rowe is a very western magic school progression series.
  
  
• The Fire Within by DK Holmberg is about a good friend that accidentally passes the test to get into magic school, then has to work his ass off to not get kicked out and forced to serve the school as a janitor. (6 books in this series right now)
  
  
• Hollow Core by Gage Lee is basically Wuxia/Xianxia High School (sequel comes out October 29th)
  
  
• Azyl Academy by Chris Vines is another Wuxia/Xianxia High School (sequel comes out November 8th) -- This book has two main weaknesses, the first is the author has way too much meta internal monologue that I think he uses as a "lampshading" trope to justify that a person positioned by a god has a lot of inherent talent (I mean, he already justified it by having a literal god intervene). The other is the lack of a coherent goal (MC just wants to "git gud" because a god told him he would be the difference between a good and bad outcome). But this series is admittedly aimed at "grade level: 5-12" (which seems like a big range to me).
  
  To me "normal" length book is 300-350 pages.
  
  > why aren't established fantasy authors rushing to deliver?
  
  New niche (niche-ier?) genre labels appear all the time, so there are probably a ton of fantasy stories out there that have that "progression" aspect to it that you are overlooking.
  
  Seriously, just climb down through Amazon's category labels to the bottom of fantasy limb and read there.
  
  The difference between "fantasy" and "progression fantasy" is how much the author details the main character(s) montages.