Indeed the HRM has pointed this out. I haven't intended to settle at this, but I wanted confirmation that the turbo intervals were indeed a little on the light side. I will emphasise however that I am 56 years old and taking medication for hypertension (high blood pressure in old money) so I tend to err on the side of caution even though I basically have no restriction other than my age to training. (confirmed by medics). As for EFR my next door neighbour has used it for the last two years. In the first year to improve his TT, and in the second as winter training for La Marmotte, In both cases it worked. Looks like I need to do Vo2 max test again. Not being precious or anything but 'utter waste'? I am sure it could have been expressed a bit more subtly than that. I certainly feel like I've had a ride at the end. I had by and large come to the same conclusion as you. Using speed as a proxy for power has obviously sold me a little short. I now realise this but only because I have ridden my last two sessions with a HRM.