Sitting. I've tried reading in bed, but I tend to get drowsy laying on my back and then it's sleepytime. Laying on my stomach propped up on my elbows makes my neck hurt after a while, so I gave up on that. But sitting? That works. Leaning back in my computer chair while reading, with a leg crossed over the other? Based. Riding on a bus that's making a Herculean effort to hit every bump and pothole in the road? No prob, Bob. Spend over an hour on the porcelain throne reading because I've lost track of time? *chef's kiss*

I read Dark Matter by Blake Crouch in less than a day.

I hate it, but I'm still going to upvote it.

"I did two things on my seventy-fifth birthday: I visited my wife's grave. Then I joined the army." -- Old Man's War by John Scalzi.

It definitely caught my attention and made me read on to see how and why he enlisted.

Another factor to keep in mind is that GRRM apparently uses an old as balls word processor from the late '80s called WordStar 4.0 and just refuses to switch to a modern one. I can't imagine that it's easy to write novels on a piece of software that's been around since the Reagan Administration.