I am returning to running after injury and it would be useful to see how well the training I am doing is improving my fitness. Garmin tells me both that that it is both no use at all and extremely effective.
To explain, this week I have had two cycling sessions with aerobic impact 3.1 and 3.2 - "impacting aerobic base" and three running sessions with aerobic impact 3.5 "impacting VO2 max", 4.5 and 4.7, both "highly impacting VO2 max". Yet I have solid "Unproductive" status from June 27 to July 7.
IMHO, it is not possible for training to be both "highly impacting VO2 max" and "Unproductive".
So unless the idea is that this feedback is purely fiction, why is there not even rough consistency between the different assessments? I would not object if it was only a difference of degree - that could be explained by differing uncertainty. But when they are at opposite extremes, something is wrong and needs fixing. The reason is that no useful decisions can be made based on feedback that tells you the opposite of what is true (which one of those must be).
I think my best unerstanding is that the "unproductive" status is saying something like "your training of the last 7 weeks has not improved your fitness". This is NOT the feedback that someone needs in general - week by week impact, or at most month by month surely makes more sense - and is especially bad when returning from injury or a break. The reason it is bad is that it is evaluating the effectiveness based on the period of no or limited training, which is now in the past and irrelevant to decisions. If it clarified this by saying "don't get injured again, it harms your progress" at least it would make sense, but "your return to training is unproductive, because when averaged with the period you had off, it is not as good as what you were doing before" is useless feedback. And that seems to be what Garmin is providing.