A cool-down does two things. It puts distance between an emotional event and the next decision, and it makes the sequence visible, since a rule you have to wait through is a rule you notice breaking.
Useful versions are short and mandatory: five or ten minutes after any loss, longer after a large one, and a cool-down after big wins too, because euphoria produces its own category of bad entries.
The one that matters most is the first minutes after a stop-out. Trades taken inside that window are, for most traders, the single worst-performing group in their record, and simply forbidding them changes monthly numbers.
Related: tilt-protocol, revenge-trading, daily-loss-limit, euphoria