A limit on how many trades you may take in a session or week, which converts a scarce resource into a deliberate one.
A frequency cap treats trades as inventory. If the plan allows three trades a day and you have taken two by 10:15, the third is expensive - which is exactly the discipline that stops boredom trades and revenge entries.
It also protects expectancy arithmetic. Every trade pays the slippage-budget, so a strategy with a +0.2R edge and 0.05R friction earns 0.15R per trade; taking twice the trades does not double the edge if the extra ones are the marginal setups that average zero. Frequency inflates costs deterministically and returns only probabilistically.
Set the number from the data: count the trades per day in the periods where your results were good, and cap near that. Most discretionary traders discover their profitable months were their quieter ones.
Original diagrams for the ideas on this page. Illustrative, not real market data.
Expectancy: the average trade. Forty trades sorted by outcome: 24 small losses and 16 larger wins. Weighting each side by how often it happens gives the average result per trade, marked here by the dashed line at +$120.Slippage on a market order. You click at 20.00, but only 300 shares are resting there, so the rest of the order fills at 20.01, 20.03 and 20.04. The average price paid is 20.02, and that two-cent gap is slippage.
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