I think people leave out the fact that their commute should also be considered time working. If you've got an hour commute and an eight hour shift, you really have a ten hour shift.

So you are taking ten hours to do eight hours of work, because part of it means dragging your brain through meatspace to be there. Since you don't have to do that, you can take longer doing the actual job.

There's also to take into consideration the fact that people experience dips of productivity throughout the day. Like, I'd never be able to start something that requires most of my brain power after 3.

For others it's early morning.

So, when I was in the office I would just kill time, go on coffee breaks or just do fucking nothing until it was time to go home, and I know for a fact that it was like that for most of my colleagues.

No one works 8 hours straight out of an 8 hours work day. Working from home just removes the torture of sticking around looking busy.

I actually complete from home the same amount of tasks I used to at the office, really, because my productivity (and that of others) wasn't constant there either.

nowadays instead of getting that work done in an 8-hour shift I take about 10–12 hours to do it.

"For disappearing acts, it's hard to beat what happens to the 8 hours supposedly left after 8 hour of work and 8 hours of sleep" -- Doug Larson.

An 8-hour shift quickly turns into 10-12 clock-hours when you factor in all the extraneous crap that goes along with it. I mean, just lunch and a commute easily adds 60-90 unpaid minutes per day. Add the time spent getting ready for work and settling down after work, and you're easily up to 10 hours a day.