How does this answer the question? You said it was common. I asked if it was really that common. What is your source? It's an important question to ask if you're designing something because it determines how much work needs to be done.
It's why I've considered adding j/k support to my blog. It wouldn't be worth the effort for most things other than a tech blog.
1. What is the width in inches of your display and how many pixels.
2. How many inches from your eyes to the screen in a normal working position?
3. Is your browser set to full screen width right now?
4. How many words per line are there across the screen in this page of hacker news on your set up?