if we started at 9 AM and finished at 5 PM, subtract one hour for lunch and count 7 hours
When we pioneered in a remote area with scattered towns, we either phoned an RV or knocked on the door of a house with lights on at 8:00 am, and then drove the 1 hour to the territory, and then the reverse on the way back, thus with a "clean conscience" being able to count the 2 hours of driving time.
The technical BS of it all.