A journal is useful because memory edits your process faster than you think. Core idea: Without written priors, it becomes too easy to remember your thesis as cleaner and more disciplined than it really was. Why it matters: Journaling gives you a record of the reasoning, not just the result. In real life: Even two sentences about the setup, the risk and the invalidation level can expose repeat mistakes later. Common slip: The mistake is waiting until the outcome is known to write the story of why you acted. Try this: On the next review, write down the one variable that would make you change your mind. A lot of confusion disappears once you separate the headline from the mechanism.