According to a recent survey, employees in many companies today work longer hours than employees did in 1979．They also take shorter vacations than employees in 1979．It seems that Americans are working harder today than ever before. Or are they? A management consultant, Bill Meyer, decided to find out. For three days, he observed an investment banker hard at work. Meyer wrote down everything the banker did during his long workday, At the end of the three-day period, Meyer reviewed the banker’s activities with him. What did they find out? They discovered that the man spent 80 percent of his time doing unnecessary work. For example, he attended unnecessary meetings, made redundant (多余的) telephone calls, and spent time packing and unpacking his two big briefcases. (76)Apparently, many people believe that the more time a person spends at work, the more he or she accomplishes. When employers evaluate employees, they often consider the amount of time on the job in addition to job performance. Employees know this. Although many working people can do their job effectively during a regular 40-hour work week, they feel they have to spend more time on the job after normal working hours so that the people who can promote them see them. A group of headhunters (猎头) were asked their opinion about a situation. They had a choice of two candidates for an executive position with an important company. The candidates had similar qualifications for the job．For example, they were both reliable. One could do the job well in a 40-hour work week. The other would do the Same job in an 80-hour work week just as well. According to a headhunting expert, the 80-hour-a-week candidate would get the job．The time this candidate spends on the job may encourage other employees to spend mote time at work, too. Employers believe that if the employees stay at work later, they may actually do more work. However, the connection between time and productivity (生产率) is not always positive. (77) In fact, many studies indicate that after a certain point, anyone’s productivity and creativity begin to decrease. Some employees are not willing to spend so much extra, unproductive time at the office once they finish their work satisfactorily, they want to relax and enjoy themselves. For these people, the Solution is to find a company that encourages people to do both. What is the main idea of this passage?