Example 1: The gap that voided the account
A trader passes an evaluation cleanly but holds a position over the weekend on an account that prohibits it. The trade is fine and even profitable, but the account is flagged at review and the pass is voided for the rule breach. The market never hurt them; an unread line did. The same outcome can come from a stop that fills five points past its level during a news spike, breaching a drawdown that careful sizing had protected all month.