Backtesting and Optimization to be pretty much essential step in trading strategy development. If the strategy is not performing well in the backtest results we can skip the system and move on to the next one. But if the backtest results are good then one should be extra cautious as most of the times backtesting your own Trading Strategy might give interesting results. However when comes to practical trading the scenario might be completely different and most of the times it results in a poor performance or lower than the expected backtest results.