Interested what people (mostly those with watches) do with their HR metrics, and how they use it to plan their exercises or their pace.

What is your rest HR? What is your maximum? What range are you typically in during exercise? What do you consider healthy? How do you use HR to determine your pace or what exercises to do? Do you have any advice with respect to this topic? Or do you think measuring HR is pure nonsense and we should not bother doing so at all?

I noticed my rest HR is at 50. My runs are mostly at 165-170ish averaged (aged 28), which seems to be fairly high. My last run (a bit faster than usual) had 24 minutes between 158-176 and 18mins higher than 176, at the end I peaked at 192 for an end sprint.