[atomicnature]

You're just making an assertion that my claim is incorrect. Practical experience shows - consistent effort does indeed deliver results, and leads to improvement in capability (by and large - as pointed in my original answer). For example, the whole education effort of 14-15 years is full of painful experiences, getting wrong answers in math, flunking in laboratories, etc. There is stress involved during the examination. If I simply avoid the exams citing stress, how'd I ever become capable?

Therefore, I don't see how you could be correct on this.

[gardenhedge]

Practical experience shows - consistent effort does indeed deliver results => agreed

leads to improvement in capability => agreed

but the assertion that those who struggle the most become the best is not proven - and I disagree with it.

"Stress as an indicator of skill/resource deficits" is also not proven

[atomicnature]

Well, life is not mathematics, so you don't "prove" things in these life matters; one simply accumulates more corroboration that particular type of mental orientation is profitable (or otherwise).

I can cite at least 20+ extremely accomplished individuals (widely acknowledged to be so) in dealing with complex fields and matters touting the virtue/power of struggling with a problem. The struggle opens up pathsways to the human being.

I'd end this with one important sentence: "There is no royal road to geometry". I believe the same mentality extends to many other aspects of life too.

PS: Even at a personal level, the greatest pleasures in life for me are some sorts of "self-mastery" - taming the beast - that is the human mechanism. And these "internal results" are obtained through great price, time and effort.