Never. There is no edge... the notion of "trading edge" is like the unicorn. There are only 2 genuine "edges".. (1) front-running, and (2) insider info. Both illegal.
Bottom line.... overall, the probability of successful trades is only 50-55%, for even the smartest of us... regardless of what others claim.
Make plays which seem sensibly "risk-reward favorable"... and be prepared to stop out losses while they are still small.
Certain market conditions provide better probabilities of success. More volatility means better probabilities bc patterns are more likely to work out. Less volatility means worse probabilities. Great traders realize this.
50-55% success for even the smartest of us ? Just because you can't break 55% doesn't mean it can't be done.