@sir82 but that does not tell us what you think it does.
For example JW's were forbidden in the former Soviet Union and East European states. So after 1990 the bans were lifted and Jehovah's Witnesses became a legal religion. The result,.. phenomenal growth during the years that followed,.. the 90's,
So the higher number of baptisms and growth can be explained easily it was not because of a certain amount of hours and effort but because of other political circumstances and improved human rights. So after that initial high growth and peak in those countries the situation normalised and a a normal growth rate remained.
Also times change. For example, during the 80's and 90's in many countries there were more people at home during the day than there are nowadays because of more traditional values and customs during previous decades. But today in many countries both males and females have full time jobs.
The result,... when you are out in service during the mornings a lot of doors wont open. It does not mean that people are less receptive...or that it take more hours now to convince a person,... but they are simply not at home.
That is why for example this year they are poundering in the KM (see for example the KM of April 2015) on field service at night or the late afternoon and through mobile carts.