I used to commute 3 hours a day, I used to finish 1-2 books per week. 3 hours of solid reading every single day.

Now, depending on the book it can be 1 week to 3 months as I don't commute and when I'm at home it's quite hard to drop everything read for one hour.

So I think it depends on people's lifestyle, if you are commuting 3 hours a day reading a book in a week is very very easy.