There is one thing to keep in mind about 'static drift' in relation to the left turn vs the chipmunk hunt
The chipmunk hunt we are talking about small distances, so maybe the phone could be stationary, or maybe he is walking around, or maybe he is running around, and perhaps inside a building.
The left turn is rather different as it is a fast moving truck on an open road.
If you turn right, you'd expect the location to track east, even if some individual data points were incorrect. It would seem odd that the data could in fact show you had gone west for any length of time.
When CAST experts are briefing Grusing, they seem to be thinking that the truck likely went briefly west, or perhaps it's just an error. They certainly didn't know BM would be admitting he went all the way to Garfield.
It's not just the location data here, but the amount of time.
If BM didn't head left - he should have been miles down the road to his destination in a totally different direction.
The missing time AND mileage can't be explained by 'static drift'