Ok, let me think about this one.
Practice and experience will improve a traders ability -Yes, if the trader is working from a good foundation. It is no good practising all the time if you are not improving on the results. Likewise, experience is of limited value if the knowledge acquired is not the correct knowledge.
System Expectancy, will TELL you where you are as a trader. Because your results are all that matter, then it is your results that you should be focused on. By focusing on your results, you will acquire additional knowledge that you did not previously have. When you apply this new knowledge to your trading, you can then evaluate your results further. If you are making improvements, then you have had some positive experiences. When one has a positive experience, one tends to think differently that with negative experiences. The results can be such that further positive experiences will follow.
Some may call this Peak Performance.
Socrates, your view please?
I will have to read this post myself - as it just flew off my head