Employers are increasingly using 5-year awards to retain and reward workers, particularly in tech companies. According to a survey conducted earlier this year, over 60 percent of companies are rewarding employees with anniversary-related compensation, which can include paid sabbaticals or cash awards. Tech firms such as Facebook provide 30-day paid vacations at employees' five-year mark as a way of retaining employees in an increasingly competitive job market, as well a means to prevent burnout among workers in high-pressure jobs. Companies are embracing these awards as a means to increase employee retention without hiking up wages.
See "In a tight labor market, companies bet big on five-year rewards", Chris Taylor, Reuters, December 10, 2018