Classification uses wrong zone model. For Z1 it combines Z1 and Z2 which is correct, but for Z2 it combines Z3 and Z4 which is wrong. It should use FTP/LTHR as an upper limit for Z2 (in 3-zone model). Here is the explanation from Treff et al:
Exercise prescription in Zone 1 is often termed “basic-endurance” or “low-intensity” exercise. The first and second lactate or ventilatory thresholds define the lower and upper limits of Zone 2, an exercise intensity that is often termed “threshold intensity,” or “lactate threshold training.” Zone 3 is usually defined as an exercise intensity greater than the second lactate or ventilatory threshold and established as high-intensity interval training near or at maximum VO2 max.
For example, if I work at 103% of FTP, this is still Z4 in Friel model, but this intensity is above FTP/MLSS/LT2 and should be considered as Polarized type of training and not threshold. Would you agree?
So that looks like a well-known bug then.
Thanks.
Just chill out. 
Seiler himself has said that polarized is about workout days. And the more hours your ride, the ratio goes even lower, and pros are like 90/10. No need to sweat (hah!) exactly your time at and above LT. I’m pretty sure he’s also said that even something in Z3/SS can be included in the intensity. It’s less about what specifically the hard workout is, but that the 80% is specifically not hard.
I would just start simple with roughly three out of every four workouts in that low-intensity range. One of them may be longer than normal, but [all three are] going to be in that low-intensity range. [And] as a starting point, if you just think of four workouts, one out of four [25 percent] is going to be kind of something like an interval session or threshold session, it’ll be tough. Mentally you’re geared up, you’re ready, you got it, you’re thinking more aggressively about maintaining a certain power.
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