i believe that's why Jun Yodaka specifically warn Hikaru to not follow his example, despite Jun still loving/can't run away from the Skate i think something happen to him that made him stop from competitive skater and how he so fixated on "Sacrifice" and also i believe Hikaru herself knows this fact for sure. Despite all that i believe Jun is kind and passionate person, he cares for Hikaru and can see people potential like what he did to Tsukasa, his reason why he always scare Hikaru that he would quit coaching her is to make her stop sacrificing everything just for instant moment of brilliance, but at the same time it is the reason why he coach Hikaru in the first place.
btw, it's all just my theory based on what we see since this manga rely heavily on the character and till now every character have valid reason to pursue their dream.
I love your theory!! Honestly I thought is just more author fiat for the quad lutz, because is very difficult technique.
i just believe because the author put so much realism in the manga already so i really doubt he/she gonna miss it (hopefully), with Inori shin splits case and Ema growth spurt case, it'll feels bad like you said if author misses this kind of details.
i really want to know more and hope to read new chapter already hahaha (〜￣△￣)〜
Honestly...with more and more difficult technique. I think the author need to recheck what kid body are capable off. If Hikaru keep doing technique that her body, realistically, her body can't handle it, it is going to ruin her. Hopefully is just one time thing or luck cause jesus. This is giving me Russian ice skating ptsd. The only way I can see Inori beat her, is litterally by sheer luck at this point, because these technique are god damn diffucult.