A pre-mortem inverts the usual question. Instead of asking what could go wrong, which produces a short polite list, you assume the failure has happened and explain it. The framing makes concrete causes much easier to generate.
Applied to a position it takes two minutes: it is a month from now and this trade was a disaster - what happened? Applied to a trading business it takes an hour and usually surfaces the same three answers: size too large, no income runway, no plan for the regime where the edge stops working.
The output is a list of specific, checkable risks. Turn each into a rule, a limit, or an exit condition, and the exercise pays for itself.
Related: implementation-intention, planning-fallacy, risk-management, checklist-discipline