I remember when only two JWs could go to a door or attend a Bible study at a time and count their time. For the six months I attempted to regular pioneer, I remember how stressful it was to get my 90 hours in. Sometimes not finding anyone to accompany me in the afternoons, and knocking on not-at-homes by myself.
It is all busy work and perhaps making inactive or DFed who are mentally in feel guilty.
Isn't the point of "door to door" vs television and radio because how "effective" talking with people one-on-one is? Cart witnessing is about not talking to people at all. I've observed carts...and the only people who notice them at all is JWs and exJWs.