Recently a crime novelist said he couldn’t understand how literary novelists take ten years to write a novel. He reckoned that nine of them must have been spent in a bar.
You cannot accuse anyone for writing fast or slow. There is the story of Stendhal writing The Charterhouse of Parma in 42 days, probably he was lying the other way around, maybe he also went some places to drink, but wrote it, I guess in 100 days. Or Faulkner who said he wrote As I Lay Dying in six weeks while working in a power plant.
There’s nothing fancy about that. But you cannot write another Great Gatsby in the next six weeks. Shakespeare did it, sometimes Dostoevsky did it when he was in his late forties and early fifties. Shakespeare and Dostoevsky, they were writing one masterpiece after another. I like to entertain thoughts about these subjects. In your youth you only desire to write great books, at my age you see the whole humanity.