As a former secretary, I'd say many of the hours are fabrications. I agree that some dubbies wouldn't fudge, but that only applies to people with real hours. Those with very low hours often "ballpark" it, either unilaterally or with some urging from their secretary or book study overseer ("You must have SOME time to report!").... Some pioneers also fudge, and I suspect many elders do, too. It's all that pressure to perform. Once a pioneer, for example, gets the "pioneer pace" down, it's not much of a leap to collate the hours in the most favorable way. I'm not talking about rounding 79+ hours up to 80; I'm talking about rounding up daily to achieve a net gain of 15 hours a month.
I worked with a lot of pioneers who were behind on their time as the end of the month neared and they had to "get in a long day" in order to make their goal. The long day consisted of gathering up friends in a car at 7 in the morning, hitting a few laundromats, then driving 60 miles or so the the far reaches of our rural territory, working a few houses, taking a break, driving around looking for someone's alleged return visit, taking another break, and so on. They'd stagger home at 7:30 that night and after collecting all the candy and food wrappers off the floor of the car, proclaim that they'd made their time. "We had a 12-hour day; boy, am I pooped."
As for elders, you can look at the cards going back for years, and it's uncanny how many of them have 9 to 13 hours a month, every month, through sickness, vacation, quick builds, whatever. They keep a running total of their average and make sure it exceeds the congregation's. They don't dare fall below that level or the CO will be all over them.
In addition, all but the most conscientious publisher goes with the herd. I can't tell you how many Saturday mornings I spent bullshooting in the parking lot, riding around, driving from one far away RV to another, taking long coffee breaks, racing back to the hall at 11:45 to drop off a publisher who had "to be somewhere at noon," and calling it 3 hours. I did that because everyone else did, too. "Well," someone would say in the KH parking lot, looking at his or her watch,"we got 3 hours in. That's great." And the rest made a mental note to record 3 hours. Except for that one sister, who suffered in silence and then went home and subtracted all the breaks and the driving time and came up with one hour. Even SHE was off by 40 mintues.
But, hey, that's my experience.