—”It depends on Season and training.”
If you follow a regular training schedule, HRV may be helpful. A Polar chest strap monitor, my phone, and the free Elite HRV app; there are many HRV apps.
Yes, for the best results, you need to take a morning reading every day to obtain a baseline. that is the hard part.
The main feature that I used was the Readiness score, on a few occasions it would suggest that I NOT do my scheduled high-intensity intervals. Not too often, but if I was out late and low on sleep...
HRV is the real deal.
Thanks, I’ll dig deeper.