I was under the impression that the same amount of material would be covered, just in a faster format. Like fewer people called on, or reading more paragraphs, then asking a question. If that's the case, it's true that you probably wouldn't wear out the book as much because you're not using it for as much total time.
Maybe I'm wrong about how much they'll cover.
I was also under the impression that the congregation has an unspoken debt for the literature. I'm sure you could find several posts about it here. But my understanding was that if the Society isn't getting a big enough "donation" back for the literature, the congregations will be cut off from future shipments.
So they are getting money for book sales. Even if one person doesn't contribute their fair share, somebody else at your hall will have to make up for it.
As it is, they have volunteer labor and their own printing presses. It's gotta be a matter of pennies to print a watchtower, but when they were still charging, they were a quarter. With computers, a lot of the costs involved with print media have been cut. Yet most people probably still remember that 25 cents figure and maybe figure with inflation, they should contribute 50 cents or a dollar per magazine now.
Let's say you buy 10 magazines a week and donate $5/week. If they only spent 50 cents or a dollar to print/ship those 10 magazines, they made quite a bit of a profit. Multiply that by 7,000,000 JWs.
If they weren't interested in making money, they'd publish their books and magazines on the internet so they could be downloaded for free. People could read the articles online and print only what they need for the book or watchtower studies.
I can understand why they moved from hardcover to paperback. It's less production costs and the books wear out faster requiring replacement. Maybe they figured you'd donate just as much. Maybe even more for the "feature" of being lighter.
But I don't know why they've cut back to things like a once-a-month Awake. Maybe because they're focusing on doctrine vs. "feel good" articles.