"The act of deciding commits you to a future you cannot fully predict.
Pressure does something predictable: it narrows attention. In a customer escalation where the facts are still changing, that narrowing turns into a demand for certainty you cannot honestly provide.
Under pressure, vague plans become brittle plans. The cost shows up later as rework and quiet blame, because no one can point to the chosen tradeoff. Define the decision rights before the crisis, or the crisis will define them for you. A clean stop line prevents optimism from keeping a failing bet alive long after the evidence turns.
Write the stop line now: what evidence ends the attempt, and what you will do when it appears. That is how you keep pressure from rewriting the decision. Let others hold you to it.