I was on the literature counter a number of years and I noticed a change when the new literature arrangement was put in place and the society no longer charged for mags and books. Even though bros. were encouraged to contribute for books they took there was a real retiscence on Bethels part to send out expensive books or publications that weren't on campaign that month. I remember bros. having to wait up to a year for things like deluxe bibles or Insight books. On every order at least 25% were back ordered.
When people payed a set price for books the publications you ordered were invariably the things you got. You did get back orders but they usually turned up at the next delivery.