I know a few JWs who barely go D2d yet they always have a report. IF i was an active witness today i'm pretty sure i could get away with not going door to door at all and still report.
I know of witnesses who "claim" to write letters and place phone calls. Others use the informal witnessing excuse. Others simply go to field service but have already arranged to go with someone they know who hates it as much. So when they go out, they spend the entire time having coffee.
Good observation.
And, how about today -- the internet age? I suspect that many (such as Mankelli) report gobs of time yet don't ever leave their shadow on a doorstep. They paste huge clumps of Watchtower text with little to none of their own commentary, thinking that new bLight will speak for itself.
Len