That was a vague statement about the effort intensity of these rides; the way I read this, however, was that your recovery rides are too hard. I wouldn't use "well below my max threshold heart rate" as the metric for these rides, but rather, making sure to stay in z1 and z2 (at the most). You should be nowhere near threshold. I'm with those who say it's not about the length (time) of the recovery ride, but rather, the intensity of it (specifically, lack thereof).