I did a little survey last week on here, the result was that out of 43, only 9 converted from door to door work, 7 of those in the 1960s.
The preaching work is not about converts. It is about keeping the flock so damn busy they dont have time to think.
And even if it was the chosen method of God, it would still not be about converts... "this good news of the kingdom will be preached in all the inhabited earth and then the end will come". It matters not whether anybody pays attention. Just the work.
Oz