Comment by 9dl

>to a device that tracks it all the time

There is the problem with hand devices and quality of measurements they do

Article describe it more properly

If you have heart problems and you need some measurements there are a lot of medical _calibrated_ devices for that

There are 0 devices for that which has only hand wearable part

Also consider such cases when such devices can do a lot of harm https://www.theguardian.com/world/2018/jan/28/fitness-tracki...

Any tech has pros and cons