Of course there are bazillions of ways to cheat on counting time. But even with "legitimate" time, consider this:
In a typical morning, a car full of 4 JWs spends 2 hours in the ministry.
But of those 2 hours:
1-1/2 hours are spent "door to door". 75% of that time is spent walking (slowly!) between doors. 75% of the doors are not at home.
Actual persons talked to? Maybe 6 between the 4 of them. Average time spent talking about the "good news"? 1 minute per "at-home"
1/2 hour of "return visits". 3 are attempted, only one is home. Maybe 2 minutes are spent talking about the latest magazines.
Time counted by the group: 8 hours
Actual time spent "giving a witness": 8 minutes
The "billion hours a year spent preaching" that the Society crows about, if accounted realistically as above, works out to maybe a few million.
As I've noted on this board several times: If there really were a "Jehovah" as JWs paint, and he really did expect them to carry out a "worldwide preaching work", he'd exterminate them in an instant for the piss-poor job they are doing.