I started precisely zero studies that lasted long enough to more than introduce the Suffer Forever book. And I can count the number of Suffer Forever books I placed on the fingers of my left hand. It is because I focused more on placing rags, just so I could get out there without committing too much time to a study. As for others, I have seen "studies" that last for a while without producing anything.
Problem? Jehovah is working against nature. There are so many regulations regarding sex that it turns off people--homophobia, bans on multiple sex partners and fornication, and restrictions against porn and masturbation work against them. They ban research that is critical of their religion--when you work against nature, you need such bans to avoid losing members. People are stagnant within the religion, and householders can sense that because it is so blatant. They are against virtually anything that is fun--Christmas, birthdays, going out a week on a camping trip, the occasional night at the bar, disco, or video arcade, and so on. It matters not that a person goes to a bar and spends their money on video games and not beer--the washtowel bans it. They lack entertainment within their own organization, which trend has developed steadily since the early 1980s. And, going to college or focusing on a career that actually pays their bills--forget about it.
I can only look forward to the time when they start having blatant negative growth. Their 7+ million--I believe it is closer to 5 million, with the number of fake time slips and false reporting at all levels. (Not to mention, if you only count the ones that are in line with living forever according to their own doctrines, it would be well below 1 million). And they bash Satan--whose followers are actually growing rapidly. That's what happens when you work with nature--you get good growth, you don't worry about "apostates" so much, and people that try it are not going to start seeing every little fault and restriction (that isn't there).