More "nose to the grindstone" does note increase the quantity or quality of your work.
Oliver Burkeman and I agree, the drive to maximize the productivity of creative souls is a surrender to the Industrial Age meme that life is best measured, with a focus on minimizing inputs and maximizing outputs. And while I sometimes veer outside his lines of focusing attention in three-to-four hour blocks, (I sometimes focus six-to-seven hour blocks on this letter, and on other enjoyable projects like a brand study), his observation that life is more than what you produce really resonates with me.
"There aren't many hard-and-fast rules of time management that apply to everyone, always, regardless of situation or personality (which is why I tend to emphasise general principles instead). But I think there might be one: you almost certainly can't consistently do the kind of work that demands serious mental focus for more than about three or four hours a day.
"As I've written before, it's positively spooky how frequently this three-to-four hour range crops up in accounts of the habits of the famously creative. Charles Darwin, at work on the theory of evolution in his study at Down House, toiled for two 90-minute periods and one one-hour period per day; the mathematical genius Henri Poincaré worked for two hours in the morning and two in the afternoon. Thomas Jefferson, Charles Dickens, Virginia Woolf, Ingmar Bergman and many more all basically followed suit, as Alex Pang explains in his book Rest (where he also discusses research supporting the idea: this isn't just a matter of cherry-picking examples to prove a point)."
Article: The Three-or-Four-Hours Rule for Getting Creative Work Done