Ecclesiastes 12:12-14 KJV. And further, by these, my son, be admonished: of making many books there is no end; and much study is a weariness of the flesh.
It's funny, they used to use that scripture sometimes to claim that secular research and study (eg: at university) was pointless, but never realised the irony that at the same time they were producing - and changing - book after book of their own.
However, I've not heard that verse used for ages now. Probably they realised how well it applies to the JW org itself, especially since they change their publications even more now, and did a wholesale dump of their "old light" just a few years ago! Now almost all the publications printed before 2010 are just so much waste paper and never referred to.
Anyone who has been in the congregation for more than about 10 years can now look back and see literature they studied diligently and were told was vital "spiritual food" has been consigned to the dustbin of history and forgotten. The Daniel's Prophecy book of the 1990s was the last one to outline in detail their beliefs of who the Kings of the North and South were through history, and it came out just after the fall of the USSR so it ended with a comment about how Russia was the latest King of the North until that point, but who knows who it might be in future?
Since then, they've not revisited the KoN/KoS history in detail, although I seem to recall there was some article recently that pretty much undid a lot of the precise explanations given in the Daniel book by saying something like "we don't know what the identities of the two kings were at every point in history, but we do know the KoN and KoS today are Russia and the UK/USA". Typical of their recent erasure of the past teachings from the Franz era.