And yet they all go back to the "cheat", "OP" and whatever other isekai trash trope ou can think about. That's not growth, that's a "get rich quick scheme" but made into a power fantasy. Plus most of the time, those "trials" early on are just bait for revenge plotlines trash.

Really, in the "trash isekai" enviroment you have two archetypes

1) Edgy revenge stuff (Shield Eho type things) where the early story is that, the character being marginalized for some reason and quickly turning that into a powerscaling thing of some kind.

2) For some stupid reason the character has an unfair advantage handed to them either from the beginning OR after grinding something silly.
The second option here is mostly set in the context of boring job and/or videogame logic, not actual self-improvement which requires discipline and effort.

It's easy to bring this into the topic of gym and stuff like that, but it's not even just that.
Studying itself requires effort and focus, not just doing mindlessly the same thing over and over.
The same applies to learning a skill. "Discipline" doesn't mean only to do something all the time in a set pattern without giving in to the desire to take it slow, but rather it means to do it with focus and intent. That's why so many eventually give up on things like these as well: they make it a habit, but not put in the will to improve.