He's the chief executive of a billion-dollar start-up, but that doesn't mean he works past 5.30pm.
Stewart Butterfield's company Slack has the internal mantra of "work hard, go home."
Business Insider reported Butterfield told a press conference on Friday that people who work 8 hours are more focussed at work.
"The most productive employees from my experience are those who go home at 5:30pm, but are hyper-focused at work," Butterfield said. "People can only think really hard for 6 to 8 hours a day."
Butterfield's Silicon Valley start-up Slack has about 350 employees and is valued at US$2 billion after just over two years of operation. He sold his photo-sharing start-up Flickr to Yahoo in 2005 for US$20 million.