Max slippage settings are a trade-off, not a safety net

[Amanhasnoname]

The deviation field on the order ticket gets set once and forgotten, but it quietly decides how the broker treats tricky fills. Set it to zero and the order gets rejected whenever the price moves even slightly. Set it to 30 points and the order fills almost always, just sometimes at a rate nobody would have chosen.

Neither extreme works well for scalping. A tight value suits quiet conditions where the entry price matters and a skipped trade costs nothing. A wider value suits fast breakouts where being in the move matters more than a fraction of a pip.

Some traders keep two profiles, one for calm markets and one for news windows, and switch deliberately instead of leaving a single compromise setting in place. It is a small detail, but it separates a controlled entry from a coin flip.

A related warning: some platforms treat the deviation differently for pending orders and instant orders, so the same number can behave in two ways within one session.

What deviation values have worked best across different market conditions, and does it ever get changed mid-session?