Working in 90-minute intervals turns out to be a prescription for maximizing productivity. Professor K. Anders Ericsson and his colleagues at Florida State University have studied elite performers, including musicians, athletes, actors and chess players. In each of these fields, Dr. Ericsson found that the best performers typically practice in uninterrupted sessions that last no more than 90 minutes. They begin in the morning, take a break between sessions, and rarely work for more than four and a half hours in any given day.
“To maximize gains from long-term practice,” Dr. Ericsson concluded, “individuals must avoid exhaustion and must limit practice to an amount from which they can completely recover on a daily or weekly basis.”
I’ve systematically built these principles into the way I write. For my first three books, I sat at my desk for up 10 hours a day. Each of the books took me at least a year to write. For my two most recent books, I wrote in three uninterrupted 90-minute sessions — beginning first thing in the morning, when my energy was highest — and took a break after each one.
Along the way, I learned that it’s not how long, but how well, you renew that matters most in terms of performance. Even renewal requires practice. The more rapidly and deeply I learned to quiet my mind and relax my body, the more restored I felt afterward. For one of the breaks, I ran. This generated mental and emotional renewal, but also turned out to be a time in which some of my best ideas came to me, unbidden. Writing just four and half hours a day, I completed both books in less than six months and spent my afternoons on less demanding work.
— Tony Schwartz, “Relax! You’ll Be More Productive“