How many hours did the CEOs work in total?

On weekdays they averaged 9.7 hours, and on the weekend days they worked, 3.9 hours.

Does working weekends make CEOs more successful?

The study measured time use only. It makes no claim that weekend work causes better results.

CEOs in a Harvard study worked on 79% of their weekend days.

About 3.9 hours each time, on top of 9.7-hour weekdays.

Michael Porter and Nitin Nohria followed 27 chief executives of large companies for 13 weeks each, logging their time around the clock. The weekend was rarely off: on 79% of Saturdays and Sundays the CEOs did some work, averaging 3.9 hours on those days.

The study describes how a small group of leaders spent their time. It does not show that weekend work makes anyone more successful, and many of the Legends in First Flight protect their weekends on purpose.

Time logs from 27 CEOs of companies with average annual revenue of about 13 billion dollars, 13 weeks each, reported in Harvard Business Review in 2018.