When the product is made by unpaid volunteers and sold by unpaid volunteers and decisions are made by unpaid volunteers who kissed ass to get up the chain, these things are bound to be a bit screwed up. It seems that back in the day, it was assumed that money would not be an issue and it was easier to run millions of each publication on the presses and put them in boxes, than it would be to run the now-needed number and run more later.
I always thought the monthly offer was driven by overstock. But there were plenty of simplistic and not-so-simplistic books mixed into older 192-page books, so I assumed the angels would make sure the householder would get what he needs.