Just anecdotally I found it pretty fascinating that I bought a new Kindle some three months ago and it still hasn't run out of batteries (came with 76% and now at 16%).
My experience with Kindles is that the battery drain is all about wifi - if you keep it in 'airplane mode' most of the time (except to send new content to it / return library books early etc.) it can last for months on a charge.
Just anecdotally I found it pretty fascinating that I bought a new Kindle some three months ago and it still hasn't run out of batteries (came with 76% and now at 16%).
Admittedly I haven't been using it a lot though.