TOP-PERFORMING CEOs come in all shapes and sizes and personalities. There are the highly gregarious extroverts who love talking and interacting with employees, customers, shareholders and industry peers. Then there are others who prefer to keep themselves away from the limelight and say no to many public engagements. And though they all work exceptionally hard, their work hours and habits vary widely. Many tech CEOs take pride in getting up at 4.30 am, starting the workday at 5-5.30 am, and then working till late in the night. Tim Cook of Apple and Elon Musk of Tesla are both known for their insane work hours. Equally, the billionaire business magnate from Mexico, Carlos Slim Helu, and his British peer, Richard Branson, have been advocating three- or four-day work weeks, pointing out…