A huge predictor of a trader's success, I find, is the amount of time they spend in learning and guiding their own development. I call this self-coaching time: the efforts that traders make to sustain continuous performance improvement.
Here are some of the best practices that I see among traders who have made a career of trading, sustaining success across years of shifting market conditions:
1) Keeping a log or journal, tracking what they did right and wrong, and always doing more of what's working;
2) Using the journal to set and pursue goals, so that they're always working on their game;
3) Taking time away from trading to develop new ideas and methods and to rejuvenate;
4) Preparing rigorously for the trading day and week, so that they're primed to act when opportunity presents itself;
5) Keeping close tabs on P/L over time, so that they can identify slumps and drawdowns early and make appropriate adjustments in risk levels and trading approaches;
6) Reading, reading, reading, and talking, talking, talking: always learning from others;
These best practices ensure that the trader is always adapting to markets, shoring up weaknesses, and maximizing strengths. It's not just the time in markets, but the time spent in self-coaching that turns a trading job into a long career.