“Normal” All-day Stress level

What do FirstBeat and Garmin consider to be a normal All-day Stress value. Somewhere I’ve seen it suggested that 1/3 of the day should consist of rest values 0-25 (8 hours), but not a discussion of what different All-Day Stress values signify, e.g., is 50 a good, bad or indifferent value? And what do we use the 7-day, 4-weeks and 12- month graphs?

I understand that HR variability has been demonstrated to track the autonomic nervous system. But, since unlike the article the FirstBeat guy recommends and the workout portion of the GCM in which you can overlay say HR and Pace, we can’t put the the Stress graph and HR graphs on one graph to try and interpret our results, therefore we’re left with a graph and a presumably a simple arithmetic average. Maybe Garmin will add this overlay capability. We can hope.