Spending too much time in the office will actually reduce your productivity.
Noah Smith at Bloomberg:
Microsoft gave its employees five consecutive three-day weekends. Astonishingly, sales per employee soared by 40% from the previous year. The company also saved money on electricity bills and paper-copying costs.
The common corporate approach is to work people as hard as possible. It's not hard to see why exhausted people aren't as effective as well rested people. It's bemusing why this culture perpetuates.