[liendolucas]

One of the things I never understood is what do you do with information such as heart rate, sleep quality, total steps you made, and so on... What is the use of all that? One of my brothers asked me a few months ago if he should buy a smart watch and I told him "what for, what are you going to get from it?"... He then acknowledged that I was kind of right. Just suggested him to use an old casio watch and what he probably needed was just a simple chronometer. That's the only metric I have been using when going out for a run. I can't possibly see what's the benefit of other metrics offered by smartwatches. And they have the disadvantage that you need to regularly recharge them.

[marcus0x62]

You use the information to monitor and guide your training, for one thing. A lot has been made about how smart watches aren't particularly accurate when measuring things like sleep or HRV (as compared to laboratory equipment,) but there is a kind of stochastic reliability good personal monitors provide. When my garmin watch says I'm fatigued (because of low HRV) or haven't been sleeping well, I see a difference in my athletic performance and can adjust accordingly to avoid injury.

It may not be super accurate at monitoring HRV, and might not even really be monitoring HRV, but it is monitoring something that correlates highly to how I feel and am likely to perform.