Trading strategies rarely fail overnight. More often, they gradually lose relevance as market conditions change. 

Changes in liquidity, participant behavior, and execution dynamics can slowly grind results with little or no warning signs. Backtests can still appear robust, giving users a false sense of confidence. This is called strategy decay, and it frequently eludes us until we have racked up some losses.

Disciplined traders monitor performance, but they also notice returns can be consistent or sluggish, order fills are reliable or imprecise and market context is helpful or challenging. The early recognition enables the modification, rather than the abandonement. The intention isn’t to constantly reinvent yourself but rather to remain relevant. 

Therefore, long-run performance depends on identifying decay before it becomes damage.