The Nathan Knorr/Fred Franz tag team had luck on its side.
On the basis that for 50 years from the early forties to the mid-nineties Fred was in charge of doctrine and Knorr (until the mid-seventies) ran the business.
The current GB and indeed most of the previous GB were of this era.
The "luck" for them was that - even after 1975, certainly up to about the early '90's - "world conditions" could be made to fit JW prophecy. The 1914 time of the end/the generation/King of the North and South/Babylon's waters drying up, all fitted the rhetoric.
Time of the end: WW1/WW2 ever present threat of WW3 (Korea/Cuba/Vietnam)
The Generation: No need to explain this ...
King of South/North: USA/UK vs USSR
Babylon: Lessening interest in Christendom in the West and in the Communist block.
It all seemed to fit - those attracted to it (along with the whackjobs) were solid families/solid wives of unbelieving husbands. Then by the early nineties it all stopped fitting the rhetoric. And in the "west" any JW growth has been at snail's pace since.
The offspring of these families and these women are the CO's and elders who were running the congregations in the Western world from the 70's to the 2000's. Since then they are dying off and passing the mantle to their sons and to the whackjobs/easily deluded.
The stability is going and only the brainwashed remain - with no Armageddon or any new order in sight.