The pioneers for the most part, couldn't care less about bearing fruit. The only thing that matter is getting those hours in and having the title of 'pioneer'. In reality the 'door to door' preaching bears virtually no results---at least in developed countries. It's far too easy for people to find out the WT's murky past including all the failed prophecies, their numerous bizarre beliefs (ie. pyramidology, Jehovah lives in Pleiades, Leviathin was really a choo-choo-train and that Jesus returned invisibly in 1914), their ban on any celebrations and the fact that you'll have to watch your family member die rather than accept a blood transfusion.
They seem to be having a bit more success in third world countries simply because many of those poor buggers are uneducated, desperate and looking for an answer to all their problems.
I don't think my old congregation has had one new person come in as a result of door to door witnessing; at least for the last 15 years. What's hilarious to see is that the KH parking lot is half empty on Sunday morning, while the church that is 2 doors down from them has a full parking lot. And they got that WITHOUT knocking on doors.