Your comment gives me the impression you feel large-scale goofing-off is a given. At one time, I would have completely agreed. No more.
Early on in my career, I often joked about being about 10% productive. When struggling with a problem, usually debugging, it was too easy to run out of steam and start surfing. I joked, but it really bothered me. So I quit. A few years later, I started in system administration for an organization that mattered. The work was fascinating, and the organization was providing a service to society that I could get behind, but we didn't have the resources to keep up. It was incredibly rare that I wasn't fully applying myself, despite regularly having to interact with some pretty toxic people and deal with intense internal politics. So there were days spent reeling from some of the questionable decision-making and the work-load was so high that there were Friday afternoons that I had nothing left to give. Even so, I probably only checked Slashdot a few times a year at work. With some effort, my productivity was above 90%, but it was wearing me down.
Now I'm happy to be in software development for an organization who's service won't change the world, but the people are great, the work is interesting, the pay is good, and work stays at work. The closest I get to goofing-off is work-related conversations that go off on tangents. Without little effort, productivity is very high.
My point is that productivity is a skill. In the right environment, it is easy to practise, but one can even learn, as I did, to be productive in toxic environments. And we shouldn't ignore our productivity in our personal lives, where it can have a larger impact than within the work-place. This is my current focus.