Ronald Reagan famously quipped that it's true hard work never killed anybody, but I figure, why take the chance? Beyond a certain level, extra effort seems to be self-defeating.
Studies suggest that, after 50 hours a week, employee productivity falls sharply. But that doesn't stop some managers from demanding that workers stay chained to their desk for long periods.
At the blood-testing firm Theranos, Sunny Balwani, then boyfriend of the founder, Elizabeth Holmes, had an obsession with employee hours, and would tour the engineering department at 7.30pm to check people were at their desks.
All those hours were wasted when the company eventually collapsed (prosecutors have charged Ms Holmes and Mr Balwani with fraud). Jack Ma, the founder of Alibaba, a Chinese e-commerce group, recently praised the 996 model,
where employees work from 9am to 9pm, six days a week, as a huge blessing. To be fair, Mr Ma said employers should not mandate such hours. Still, presenteeism is the curse of the modern office worker.
There will be days when you do not have much to do, perhaps because you are waiting for someone else in a different department, or a different company, to respond to a request.
As the clock ticks past 5pm, there may be no purpose in staying at your desk. But you can see your boss hard at work and, more important, they can see you. So you make an effort to look busy.
Some of this may be a self-perpetuating cycle. If bosses do not like to go home before their underlings, and underlings fear leaving before their bosses, everyone is trapped.
Staff may feel that they will not get a pay rise, or a promotion, if they are not seen to be putting in maximum effort. This is easily confused with long hours.
Managers, who are often no good at judging employees' performance, use time in the office as a proxy. The consequence is often wasted effort. To adjust the old joke about the Soviet Union:
We pretend to work and managers pretend to believe us. Rather than work hard, you toil to make bosses think that you are.
Leaving a jacket on your office chair, walking around purposefully with a notebook or clipboard and sending out emails at odd hours are three of the best-known tricks.