Welcome to 2017:)
My local Discount tire and les schawb does not have their air system up to standards, if there are any. Their torque wrenches are calibrated by 3rd party vendor for liability purposes. But very disappointed by one air regulator on top of shop air compressor sitting in back room and lots of people using air system at once. I asked about regulated PSI of their air thru out their air plumbing. So that they know exactly what psi they are filling to using a tire gauge that they know is accurate. Their answer was "nobody said there was a problem yet".
I resort to using my own compressor. All three of my air gauges are within 2 pounds of each other. After tire work I have resorted to completing the job the next day when tires haven't been used for at least 12 hours.