Hanyu won the Olympics. Figure skating is a two-part event. Hanyu's programs were more conservative than Nathan's but PCS wise they were on another level, he skated cleaner across both programs, and he won the event. Nathan didn't even medal. (Hanyu earned about 10 more points in PCS than Nathan in the LP as well.) Hanyu also narrowed the TES gap through earning more GOE.
And Nathan isn't Hanyu's only competition. Hanyu beat Shoma in the LP due to PCS, even though Shoma had him beat in TES. But without Hanyu's great GOE, the PCS advantage wouldn't have been enough. Shoma had him beat by 10 points in BV, but with GOE, that gap narrowed to 2 points, which allowed Hanyu to win.
Hanyu also had a pretty great lead going into the LP because of his stunning SP. While Javier and Shoma both skated clean (and Shoma had higher BV than Hanyu), Hanyu's PCS + GOE had him well over both in points.
Hanyu wouldn't have been able to do this without working the heck out of his skating skills + performance abilities. (And let's not forget Javi, who has hung with the top guys despite never trying anything harder than a 4S and 4T in competition. Shoma had a 23 point advantage in BV in both programs, but Javi only lost to him by ~1 point).
Evgenia should maximize everything she already has while also working on training potential BV increases. But I'm not sure how likely it is for a grown woman to get a reliable quad.
Judges might not start marking Alina down in PCS, but when the junior Eteri girls go senior, they might be more reluctant to significantly increase their PCS if Evgenia makes herself basically untouchable in terms of SS and performance ability.
I will just show numbers from the Olympics.
Hanyu PCs: 48.50 (SP) + 96.62 (FS)
Nathan PCs: 41.88 (SP) + 87.44 (FS)
1. A perfect 10 would bring Hanyu only +4.88 points above his score (btw, this is why he is working on harder quads lately, because his PCs are basically max possible, stronger SS or musicality will make no difference, because his PCs can't get any higher).
2. The difference in PCs between Nathan and Hanyu is 15.8, which is a big deal.
Medvedeva: 38.42(SP) + 77.47(FS)
Zagitova: 37.62(SP) + 75.03(FS)
The PCs difference between Zhenya and Alina is of 3.24 points across 2 programs. Also, Zhenya is only 4.11 points away from the max possible PCs. There is no room to improve, and there is no room to win over Alina either, because both are pretty close to the max cap.
GOE now:
Hanyu: 14.17(SP) + 16.99 (FS)
Nathan: -6.09(SP) + 12.53(FS)
Medvedeva: 10.09(SP) + 16.85(FS)
Zagitova: 10.33(SP) + 15.61(FS)
There is no GOE gap between Zhenya and Alina, and both don't really have that much room to improve, since they were getting all +2/+3 on everything already.
In short, I don't think the situation with Nathan and Hanyu is whole different, and not a good comparison.
As for juniors, I think it is debatable. I mean, look at Kostornaia. She is already better than Alina in PCs categories. Will judges mark her down simply because she is young? Debatable. Kostner is untouchable in terms of SS and performance ability, and Alina still gets 9+ on her first senior season =) Just saying.
I would say that, for Zhenya, improving in PCs is irrelevant. It will make no difference to her scores, or to how everybody else is scored.
Her GOE is currently nearly maxed out, and the only thing she may work is the size and the flow and the effortlessness of her jumps, to make sure she nails those first 3 bullet points.
Not only that, but her competition has it easier to improve - take the Eteri girls with full backloading, for example. They need to hit those 1,2,3 GOE bullets? Just move 4 jumping passes to the first half and they got it.
Her BV is her weakness, because her competition has higher BV, and gets nearly same GOEs and PCs (which are maxed out). We are yet to see the new GOE scoring, but i see how her lower BV may hurt her quite a bit. a +3 3Lz is worth more than a +4 3S, for example.
Yes, she may not learn a quad, but i think if she doesn't fix her Lz edge, working on SS and musicality is pointless.