Way back when I was a fledgling dub, I remember an elder counseling us at the meeting for service about keeping accurate time. One of the things he cautioned against was being too fanatical (my word, not his) about it. He used the illustration of two publishers working together all morning, then one counting their time as one hour while the other recorded two.
The first, he said, was subtracting all the time between doors, the 10 minutes when they stopped for gas, and the 15 minutes they stopped for coffee, while the other counted time from when they got to the first door to when they left the last door. He said it wasn't necessary to discount the time by a few minutes here, a few minutes there, as long as that was directly related to the FS activity.
I was later to learn that he failed to mention the "third" publisher, the one that counted time from the moment he left his house to the time he got home; he got three hours that day!