As an engineer, it's not as easy to get through technical books in such short amounts of time.
Reading x books doesn't count as learning x topics.
And then you can mix in other readings. A chapter in a technical book may only survey its particular material, but you may want to explore the ideas further. So you go out and get some papers to read or another book.
I may not finish many books in a year, but I do get a lot of reading in.
Even though I love fiction, I couldn't pick up a second book from Stephen King without fully finishing the first. I'd lose interest in the first one otherwise.