TD
I agree with you. The biggest increases were in the early 1950's. The "generation" of 1914 was still young enough to lead. The nuclear age had just begun. There was a clear King of the North & King of the South. The large 8-day Assemblies were "real" movements and solidifying experiences. The decision to get baptized was spontaneous and heartfelt NOT contrived and subject to a tribunal. The world itself was almost as authoritarian as the Watchtower. The speakers at assemblies had freedom to express themselves creatively - so they were less boring.
People were rarely disfellowshipped. You could speculate all you wanted without anyone accusing you of apostacy. The blood doctrine was vague. You could neck and pet on unchapperoned dates without being brought before the judges. Congregations could have competitive baseball games and big congregation picnics. No one was disfellowshipped for smoking. There were basement parties for teens about once a week in the big metro areas.
Almost all young men were pioneers to avoid the draft. Young men could have serious teaching positions in the congregation at the age of 14. This was important to me because it kept me busy in a creative way.
It all started to fall apart in 1966 with the setting of the 1975 date. Every year the organization kept tightening the noose. When the 1970's started the organization became obsessed with cleaning up before they entered the "promised land/ New Order". They thought the end was near so they broadened the definition of fornication to include petting and necking. They felt they had to be free of those dirty filthy smokers. The final step was to create "elders" who could govern the congregations. These were men that were previously side-lined because they were horrible speakers but now they could share in "shepherding" bossing and policing everyone.
The organization is a jet airplane with both the pilot and co-pilot dead of food poisoning.