Three levels of thinking in trading

(1) Individual stock
The behavior of individual stock is random. Even 2 stocks look identical: chart, fundamental, float, market timing... and etc. Still one may b/o successful while the other one may not work.
    The effort in this level is: found a setup, thinking in probability and trade in discipline. Psychology issue will kick in at this level also, which need to be resolved.

(2) Setup behavior
When we think in setup, it is a group behavior. There is a distribution of stocks with same setup. For example, for short term swing setups. Your win/loss tradings is like 1:1 ratio; average rewards/loss in $ is like 2:1; 20-30% of chance you will catch idea move; 30-40% of chance it goes to reverse direction of your expectation and may hit stop loss...
    This distribution is affected by generally market and keep changing. For example, at early bull market, b/o success rate will be high. During market top, it is very vulnerable. Years ago, best quality stock move first in a rally, then 2nd quality and then others when everything moved up, it is about to turn; now this is change, all stocks move when bear market end and most beaten down stocks b/o strong at early rally.
    The effort in this level, market timing tool is very important. Also effort need to keep monitor the setups. If something changed, is it due to market condition or setup behavior is really change?

(3) Long time endure edge.
Long time endure edge: most trad-able edge is momentum and PEAD (Post Earning Announcement Drift). The setup need to be built on endure edge in order to profit. Momentum and PEAD has been there since market beginning and likely to persist in our life time.
    Setup keep changing, but what really changed is the tactics. Buy b/o changed to buy pull-back or buy end of day changed to buy during the day or use 3 months to gauge momentum instead of 6 months ... something like this. But momentum or PEAD itself is really not change.
    The effort in this level, belief system really need to be in line with these endure edge. Extensively studing them will convince yourself. There are tons of research work in public domain since 1980s, we are very lucky we do not need to do everything from the beginning again. The thing is you still need effort to study them to get convinced. Or you will believe something else (market is manipulate, market is efficient and no edge, low PE works, great traders has some secrets, if everyone know it, then edge will disappear ...)