freddo and alanv,
All that we have is perspective and an opinion out of what we see. My mother participated in a week-long cart witnessing drive at a local book fair (in India) and the entire group placed 1000 pieces of literature in total. If this gets printed in any JW literature, it would be enough fodder for all JW's across the world to continue their cart work no matter what the results are.
Regarding KH crashing and picketing, two things stand out: One, even the Ex-JW world is divided on the effectiveness of this. Two, the videos uploaded are viewed and commented upon by other Ex-JW's. I am not sure if the world takes notice of these things. We don't have any independent and unbiased view on this.
My point was that many individuals participate in these activities for personal satisfaction (praising Jehovah, etc) and hope that they have some results. A JW feels that he cannot convert a person unless Jehovah draws him, while an Ex-JW activist feels that he cannot awake a JW unless he opens his mind. A JW who is unable to place a single literature during his cart work goes home happy thinking that he has made Jehovah proud and hopes someone will visit the website. Same is true of an Ex-JW activist who goes home after a KH crash or a picketing session.