A stop written down in advance

A limit on losses within a session or a week, decided at a time when nothing is at stake and applied without renegotiation when it is reached.

Decisions made mid-session are made under exactly the conditions that degrade them: recent losses, tiredness, and a strong desire for the evening to end differently. A rule written on Sunday morning is not subject to any of that.

A stop is not a prediction that you will need it. It is insurance against the one evening in fifty when the usual controls do not hold, and it costs nothing on the other forty-nine.

Which is where it goes wrong. The moment a stop is most needed is the moment it is least likely to be invented, which is the entire argument for writing it beforehand.

What to do with it. Write a session limit and a weekly limit down, in currency, and put them somewhere you will see them before betting rather than during.