I was a little surprised that so much of my training was in Z2 when I expected more in Z1. However, upon further, investigation there seems to be something very wrong with the algorithm calculating time in each zone. I edited my HR zones several times, including making the Z2 range 175-176bpm (should be a very small amount of time spent at such a small & high range) and and no matter what it said I spent around 44 hours in Z2. It is mathematically impossible for me to spend 66% of my time at 175-176bpm and 67% of my time at 144-157bpm (see screenshots).