Bill Gateshacks his email with a larger three-monitor display area. One set is on the emails he's working on, and the last screen for a regular desktop. This way, he can multi-task more successfully. He goes on an annual Think Week to a cabin in the woods to completely unplug. He takes with reams of documents and books. This way he gets a year's worth of reading and thinking in a week. He also goes over his past year and plans for the future.
Elon Musk has three executive job titles, five kids, and is wildly ambitious. He officially clocks in no more than 15 hours at the office but has said he doesn't ever stop working. With this schedule, he still averages 6 hours of sleep a night.
He multitasks by sending emails while scanning invoices, holds meetings and takes care of business on his phone at the same time, and texts with his children on his lap.