I always wrote by hand - probably because I spent over a decade in academia dealing with equations. I always have a pen in my pocket (without a pocket protector!)
About a decade ago I went back to writing with fountain pens after a nearly two decade hiatus. Oh, the joy!
But very sad he has no (real) tips on dealing with hand fatigue - other than to write in cursive. I always had hand fatigue for writing long stretches of prose - even back in my school days. A few years ago, I simply had to change how I grip the pen to reduce the pain, but I still can't write many pages without significant pain and the need for breaks. I can't imagine writing a whole novel that way.
Also, I wish he told us how he gets that handwritten stuff into digital form. Does he just mail handwritten stuff to the publishers?
In the past, I'd write twice: Once by hand, and then I'd type up anything worth saving to get it in digital form. A royal pain!
Then with Whisper and LLMs, life got a lot better. I would simply read what I'd handwritten, and get an LLM to clean it up. I only occasionally needed to fix it up after that.
Now LLMs are so good at it that I simply take a picture and send it to the LLM for transcribing.
I don't care how much people hate AI - for me it has quite literally reduced physical pain in my life.