back in the 80's and 90's the km had inserts about the use of magazines and mentioned there were major differences between the number of magazines produced and the amount reported as placed.
I remember parts on CA programs discussing this. They ackowledged there must be a large number of magazines in pubs homes and book bags that need to be placed or the number ordered should be reduced.
Remember too, that only literature placed with non witnesses can be counted in fs reports. When they had personal subscriptions none of those copies were included on FS reports.
Having pubs report tract placements makes sense too as the society can monitor how many are shipped/reported as placed, and adjust the amount printed and shipped to congs accordingly.
The volume they print is enormous, most years the total Bibles, books, tracts, brochures, magazines and booklets produced comes to between 2.5 and 3 BILLION!
I cannot imagine all the work involved and logistics of having all of this work done in over 700 languages, much of it simultaneous with English and shipping it all out on time to reach all of the congregations during the same week.