How do Ag Exemptions Work in Trucking?

I have run raw milk from and back to the farm since the Ag Exempt started with an ELD. You can use the 150 mile radius or go by 172 statute miles from the farm. For instance I would log in and enter Personal Conveyance, and then notated Ag Exemption- 49 CFR Part 395. Run 172 miles, then enter On Duty/ Driving. Make my delivery, and if returning to the same farm, drive back to that same spot that starts my 172 statute miles and enter into PC- Ag Exemption once again. Notated the same way. But you do have to be back to this spot within your 14 hour period. Been stopped and inspected a few times, and 0 problems.