Jul 14, 2021
Let's do some arithmetic, okay? A typical page runs 250 words. 300 pages = 75,000 words divided by 15 hours = 5,000 words per hour or 83 1/3 words per minute.
That's not realistic because even a prolific writer like Stephen King writes ~6 pages per day or 1500 words. I once knew a person who published 2 books per month (before he got banned from Amazon) with about 60-80k words per book. At that rate, it still takes 2 weeks for him to write up so many words.
I think a more realistic depiction would find your MC with a half-written work on his computer, and he uses the notes to complete the story.