Well when i'm writing I shoot for at least 1.5k-2.5k (though I dont always hit that.) When reading I don't really care as long as the the pacing is good.
I don't want to read a chapter over 5k that has a lot of needless fluff that dosent add anything.
The book Way of Kings has a lot of different perspectives and it bounces from heavy stuff to slightly less heavy stuff a lot. (All though the whole tone of the book is serious).
I think slice of life could be a nice way to give some breathing room from all the heavy serious stuff though if you...
Do just enough to give the reader a feel of what is happening. Don't go into too much detail cause that ruins pacing and don't even bother trying to get the reader to see the fight scene exactly as you see it in your mind cause you can't.
Sword art online. It was the first time I realized that a media I was consuming was really fucking bad and I wanted to know why. Now I have a problem with over analyzing everything and I struggle to just sit down and enjoy something.
I just started writing recently so I haven't hit any burnout yet. I'm going to keep myself on a schedule so I can avoid hitting one as long as possible.