A study published by U.S. Travel Association indicates spending more time at work often doesn't pay off:

"Workers who left 11 to 15 days unused during a year were 6.5 percent less likely to receive a raise or bonus than those who used all of their vacation days."

Another study conducted, by an audit organization known as EY, shows that annual performance review scores increase 8% with roughly every 10 hours an employee takes on vacation.