Near the end of the page linked to above, there is this.
After Scientologist (or perhaps 'I'm not a Scientologist but . . .'), Rachael Fisher congratulates Ryan on his production, Anna and Élie query him with, "That's roughly 30 seconds per letter. How?" and "What's your trick?"
Let me attempt to answer this based on my own experience writing letters for Scientology, and receiving letters from Scientology.
Firstly, in my opinion based on my experience and ongoing deprogramming activities, people in Scientology, and especially those who are staff members working for Scientology, live in a hypnotic trance state reinforced by continual exposure to Hubbard and the application of his techniques and doing TRs (training routines). That would account for Ryan's belief that his letters were, "all individual letters, from the heart, and fully written with interest."
However, I have a strong feeling that all of his letters were one or two sentences in length, making his heart feeling and interest very pithy indeed.
Most of the letters I have written for Scientology or received from Scientology have been along the following line.
How are you? Have you read Dianetics? Let me know how you feel about it?
I got one letter from a person in a mission when I was on staff in a class 4 org. (They're class 5 orgs now.) It went something like the following.
We are on an all hands writing letters to get our letters out stat at highest ever.
(By the way I never met anyone named Julie while I was involved with Scientology. But if you must, office of special affairs lurker, search away.)
So there's how one writes 230 letters in two hours, and an insight into Ryan's trick.