I have average size arms. No human taking my BP has ever switched to a non-standard cuff size for me. And yet, when I tried a consumer-grade automatic arm ban

I have average size arms. No human taking my BP has ever switched to a non-standard cuff size for me. And yet, when I tried a consumer-grade automatic arm band blood pressure test, we couldn't get it to read within 100 mmHg of what any other machine or person had ever gotten. It was consistently claiming something crazy like 250/150 for me, though for most other people's arms it seemed to be somewhat more reasonable. We tried rolling up my sleeve, un-crossing my legs, the whole nine yards. We even pulled out a stethoscope and had some of us (non-medical-professionals) listen to my arm, and nobody had any trouble hearing the change. No doctor, nurse, or phlebotomist has ever had any trouble taking my BP, either. I am apprehensive of expensive, complex machines that attempt to replace what a human can do by hand in about the same amount of time with only a tiny amount of training.