I remember a local needs talk one time about 15 years ago...
It was a part on "How To Count Your Hours In Service"
So after you leave the hall if you drive to the territory you count your time when you get out of the car to bang on the first door. However, if you bang on a Return Visit right next to the hall then you can count your drive time as "Service Time".
If a break is necessary to continue "Witnessing" (ie a 15 minute pit stop at a Mickey D's) no need in deducting that time.
If you go over 15 mins or so.... then it is a "break" and should not be counted.
He also said, "I've noticed recently teenaged ones having a little too much fun in Service... we need to remember this is serious business".
He concluded by saying that you should never round up your service time, but carry over the time. So if you have 10 hours and 45 minutes of Service time, then you turn in the 10 hours and add 45 minutes to next month. But you should never round up and deduct the 15 minutes from next month, because this was like robbing Jehovah.
This was the same elder who a few weeks earlier laughed at the Jewish leaders of Jesus time for debating whether wiping their noses on the sabbath was considered work or not.
Who sounds more ridiculous?