I started out being very vigilant about time-counting. I would carefully track start/stop times, would discount time spent on any breaks, etc. I would round to the nearest 5 minute interval at most.
I very quickly became disillusioned with the regular pioneers, though. They would take two-hour lunch breaks without discounting any of the time. If pressed, they would often try to justify it by pointing out some unbaptized publisher who was in attendance, almost always a young child of a pioneer. Mostly, they didn't care, though.
Once I became a regular pioneer, the falsity of time-counting became even more apparent. One of the regular pioneers was a recently-appointed elder. One time he and I had spent about an hour and fifteen minutes knocking on doors. I asked him how much time we had spent (I had forgotten to document the start time) and he said to just write down three hours because "we were pioneers." There was another guy who we'd almost never see in service, but he was of the opinion that if you were doing yard work, for instance, that was a witness to your neighbors and therefore time you could count.
I was only a regular pioneer for a year and a half. By the end of it, I'd more or less adopted the general philosophy held by the group. Swimming upstream was just too hard, but i was pretty disgusted with myself for doing so.
This whole cart-witnessing thing, if officially sanctioned by the WT, would have been a god send for me. I would have been able to get away with counting a ton of hours without the guilt associated with feeling like I was cheating. Thankfully, I have better things to do with my life now.