This is an interesting point. I know for sure that I have been taught in school to never trust the electronic BP machines, since they can be pretty far off for some (but not all) people.

Instead, using a sphygmomanometer is much more likely to give accurate results.

Anecdotally, I always have a super weird initial blood pressure reading when I go to the doctor and they use the electric machine (one time it was 112/95), but when it is rechecked with a sphygmomanometer it tends to level out at somewhere around 130/85.