It's not always consciously slacking off. For example when I was at Google most of the team was simply incompetent. They thought they were smart (PhDs!) and working hard. But they refused to work together. They estimated tasks in weeks and months and at the end of my time there after I'd done very little due to obstruction by other teams I was praised for my high productivity.

I never saw anyone just sitting around or really slacking. But they couldn't execute anything. It was depressing.