The concept of the "85% rule" suggests that achieving better developer performance can be achieved by working at an optimal level of effort, rather than exhausting oneself with maximum intensity. Research and studies have shown that peak performance is often reached when exerting energy at around 85% capacity, allowing for sustained focus and avoiding burnout. By embracing this approach, managers can unlock practical ways to boost developer productivity, such as encouraging a "done for the day" cutoff, asking developers to work at 85% of their maximum capacity, fostering open communication about deadlines and challenges, seeking optimal decisions, ending meetings early, and reducing pressure on perfectionism. This counterintuitive insight reveals powerful truths about productivity and can lead to improved outcomes, including reduced burnout and higher-quality results.