The big reward is that you get to be hounded to pious-sneer all the time. First, they lower the requirement and then state that, with the new lower requirement, everyone should do it. Anyone not pious-sneering during these periods is inviting Brother Hounder to hound them. Brother Hounder will not leave you alone until you commit, and you better fulfill it with no excuses or else.
Once you are in at the ground level, they up the ante even worse. "You are doing the 30. If you truly love Jehovah, you would do the 50 instead." Never mind that many people are barely in a position to do 30, and it requires a lot of sacrifice. I can remember when I was first going into the cancer--the second month in, I got 32 honest hours during that month. It meant not doing a lot of things for myself, and I could not see myself stuck doing that every month. Yet, they insist that you should do that all the time. Then, once they get 30, they want 50. Then, through a great deal of hounding, they push you to regular pious-sneer at 840/year. The guilt that it used to be 60 for everyone and 150 for pious-sneers is imposed--if they could do 150, why can't you do 70?
From there, "Why stop at the minimum? It's for joke-hova! We love joke-hova so much that we are willing to give up ANYTHING for that thing! You should be putting in the 90 or 100 hours a month!" Then, they up it to 200 hours a month. Where do they stop? All from those little steps. Rather, they should just let each publisher decide (without hounding--if they get hounded, they don't do anything at all) how much is enough. How much do they do before the actual marginal cost of doing the next unit exceeds the marginal benefit? That is the optimum level, and can fluctuate from one month to the next. And the hounders can drive that optimal level down by hounding the people to do more. Of course, if the optimum level is at or below zero, then zero it shall be.