I've tried every productivity system out there—Pomodoro, time-blocking, GTD—and after a decade of experimenting, I'm convinced that the 8-hour workday is the real enemy of personal productivity. Our energy naturally ebbs and flows in 90-minute cycles, yet we force ourselves into rigid, continuous blocks that ignore our biology. I've seen colleagues burn out trying to sustain deep focus for hours, while my own output doubled when I switched to two focused 3-hour sprints with long breaks in between. Is it time we abandoned the 9-to-5 model for good?