All of my workouts are custom (from TrainingPeaks) and outside. For awhile, maybe 2-3 months, outside rides were automatic passes and I saw progression levels increases. Everything looked reasonable, except there didn’t appear to be any decay. Then I took 5 weeks off and restarted serious training last week. Thats when I saw decay in the levels, because during the 5 week off-season I only looked at progression levels in late August and perhaps early September (and was surprised to see no decay). So at some point in September, probably the 2nd half of the month, it appears that TR enabled decaying PLs. While I can understand the value of TR plans and PLs if someone simply wants to be told what to do, I’m not finding any value in the PLs.
And yesterday I saw some wackiness in PLs: Progression level decay - #21 by bbarrera
Hope that helps.