Musk goes one further and suggests people put in 80 to 100 hours a week at work if they want to "change the world". On Twitter last year he said: "Varies per person, but about 80 [hours] sustained, peaking above 100 at times. Pain level increases exponentially above 80."
Both business leaders have faced criticism for their remarks from commentators who suggest that overwork could lead to decreased productivity among staff.
Not only is there little correlation between working longer hours and better productivity - recent data from the Trades Union Congress show that full-time employees in Germany work 1.8 hours a week less than those in the UK but are 14.6 per cent more productive - there is a clear link that overworking leads to stress, fatigue and sustained sleep deprivation, which can in turn create mental health problems.
An estimated 15.4 million days were lost in 2017-18 due to employee mental health issues, such as stress, depression and anxiety. The combined economic impact of mental health-related absence on UK employers is expected to reach £100 billion ($193.8b) this year, claims the Centre for Economics and Business Research.
In Japan, where around 20 per cent of the workforce put in more than 80 hours of overtime a month, the number of legal claims relating to "karoshi" - meaning "death by overwork" - rose to a record high of 1,456 in 2015-16, with employees taking their own lives or suffering from heart failure and strokes because of long hours.
Ma's recommendation of a "996" working culture is also problematic because it breaches Chinese labour laws, which require that an employee's work day is no more than eight hours, and an average work week is no more than 40 hours.
An employer may require certain staff, such as high-ranking managerial staff and sales staff, to work in excess of 40 hours per week, but usually they will have to pay overtime as compensation.
In Britain, employees cannot be forced to work more than an average of 48 hours a week unless they agree to put in additional working hours and confirm this in writing.
Will Stronge, co-founder of think tank Autonomy, which advocates a shorter working week, said Ma's comments were "dangerous in an industry where long hours (often unpaid) are already imposed on workers, often in the name of 'commitment', 'drive' or 'loyalty ' to the company".
"Working 72-hour weeks would take us back to the 19th century - where staff worked similar hours, had very little protection from the whims of their bosses and their physical and psychological well-being were not considered. The future of work should be one in which we continue to decrease the working week, whilst retaining wages - as we have done in the past," he says.
A number of companies have done the reverse of what Ma suggests, by introducing four-day working weeks in the hope of reducing burnout among staff and increasing productivity.
Just last week, an Australian tech firm said that after giving employees every Wednesday off to relax, its revenues rose by a third.
Radioactive PR, an agency based in Gloucester, implemented a four-day week last September after a successful six-week trial in which staff reported having a better work-life balance.
Trials of shorter weeks are not always so successful, however. After announcing in January that it planned to move all 800 staff members to a four-day week, the Wellcome Trust recently decided that it would scrap the initiative, admitting it would be "too operationally complex to implement".
Had the biomedical research foundation, the world's second-biggest research donor after the Bill and Melinda Gates Foundation, adopted the policy, it would have become the largest organisation in the world to do so.
Could 12-hour days become the norm in Britain? British employees are working longer today than they did a decade ago - about 30 minutes a week more - according to the Office for National Statistics.
And this figure doesn't include unpaid overtime, which has become increasingly common due to the advent of email on smartphones, and the booming culture of "presenteeism".
Once defined as an employee coming into work when unwell, the term has been broadened to refer to staff who arrive early and/or stay late at the office just to be seen at their desk - as well as those who respond to emails at all hours of the night to show they're still thinking about work.
Some people have suggested that Britain leaving the European Union could herald the start of lengthier working weeks, as the Working Time Regulations have long been seen as a target for post-Brexit deregulation.
However, Jane Amphlett, partner and head of employment at law firm Howard Kennedy, says any post-transition period deal with the EU is likely to entail the UK complying with EU employment and consumer standards to a large extent, "so there may be little scope for radical change".
"British employees can already opt out of the 48-hour week limit required by EU law and many employment contracts (particularly in managerial or client-facing roles) include such an opt-out. So UK employers already have considerable freedom to set hours," she says.
"In any case, EU law isn't the only obstacle to long hours. Employers have a duty of care towards staff and are required to provide a safe system of work."
