The problem
After one or two losses clarity drops: you enter to win it back, widen the stop, increase the size. These are the worst trades of the whole month.
The rule
Decide a limit in advance: two consecutive losses, or a maximum daily loss in R (for example −3R). When you hit it, close the platform until the next day.
Add wider weekly and monthly limits: they protect you from longer losing streaks.
Make it automatic
Willpower runs out exactly when you need it. A journal that blocks new trades when the limit is hit makes the rule impossible to ignore.