Re: RHR and HRV, in my experience there are no hard and fast rules that are broadly applicable. For every person I’ve seen that has HRV trends that fall into the generally accepted thumbrules of “up good, down bad”, there are people for whom HRV seems like a random number generator (ME!).
I think with this stuff it is important that you track your own data and analyze your own trends and behavior for a long enough period of training that you can then draw your own conclusions, rather than worrying about what other people say or what Oura or Whoop or Garmin Body Battery tell you.
If you’re one of the lucky ones for whom those devices and measurements seem to work, great. In my opinion, HRV/RHR data is better as a supplement to your own subjective feeling. One reason I still track mine on a daily basis using HRV4Training is that it forces me to spend a minute each morning reflecting on how I’m feeling - mood, energy, soreness, sleep, etc. As I do that, I have a pretty good idea of if I want to train as planned that day, or maybe go a little harder, or take an unplanned rest day, etc. And I get that idea well before I see what my RMSSD or RHR or HRV4T’s recommendation is.
Most often, when I feel like trash, it’ll be reflected in something. Conversely, I have plenty of days where I feel great, RMSSD is a bit low, and I have a fantastic workout in spite of that.
I do take note when I have days where things are out of whack with those numbers, and if they start to string together and other things like body temp or sleep are affected, then it’s more important to pay attention and back off. But as one-off data, I do not personally find all that much day-to-day use out of HRV/RHR.
That said, someone mentioned long-term trending, and I do pay attention to my baselines. As RMSSD baseline comes up and RHR drops, my fitness generally improves, so it is a marker for me to know that things are going in the right direction. That said, I think my HRV will just continue through onto the moon if I just keep training… and then when I finally take rest, it usually drops like a GD rock for the first few days, and remains depressed until I get back to training.
TL;DR - it’s most important to know what your data means for YOU, and that’s going to take some time and analysis on your own part to know whether using that data is meaningful for you or not.