I think those lab definitions match those in the book. LT=AeT (top of Z2) and LTP=AnT (top of Z3).
15% AnT/AeT difference according to the calculator: https://uphillathlete.com/aerobic-training/uphill-athlete-training-zones-heart-rate-calculator/
I’m new to this too, but I think a few months of training in the upper 150s bpm will show an improvement. I have seen it in myself. When you run at that intensity for up to an hour, how does it feel?
I wonder about the language of ‘suffering from ADS’. You’re only ‘suffering’ and ‘deficient’ relative to high performance aspirations of a small group of endurance athletes. Compared to the general population, you appear to be very fit and if you aspire to perform well in endurance sports, then training targeted in upper Z2 is likely to be beneficial for that aspiration.