Though it may not always be precise, I know this from being part of an Army National Guard (Transportation) unit. Trucks get started and allowed to sit and idle for a short time, (muck like the soldiers in the unit), on drill weekends. It is part of their monthly/annual PMCS, (Preventive Maintenance Checks and Services). An occasional, "once around the block," then, "Shut 'em down and go to lunch," was often the agenda. Believe me, vehicles in many National Guard units, SIT! A LOT! Going on an annual training mission did not often require us to even bring our vehicles. And if it did, it was loading practice. Practice loading the vehicles on and off
other, usually contracted commercial vehicles. Often trains.
I know the odometer and hour meter can be changed out easily enough, but if the gages and meters are all about the same condition, there is a fair chance they indicate the truth. That's in many, but probably not all situations. I have faith. (We all do, but sometimes we go with a default answer like, "they can't be accurate" to cover our disappointment if we discover something down the road).
If you do the calculations, average *40 mph, v. actual hours, does it fit?
A truck with 25,000 miles, driven an average speed of 40 mph, would register 625 hours. That doesn't include idle time, but...??? Close?
I bought my deuce with 26,700 miles and 1043 hours, or something close to that. It seemed about right.
* I say 40 mph because you cannot take off at 55 mph. I've tried. It doesn't happen in a deuce.