Automation is mostly risk plumbing
Entry signals get the attention. Lot sizing keeps accounts alive. Automated copy stacks need an explicit rule for how slave volume relates to master volume.
Fixed lots
Predictable. Easy to audit. Poor when equity differs widely across accounts.
Proportional lots
slaveLots ≈ (slaveBalance ÷ masterBalance) × masterVolume. Scales with equity. Sensitive to stale balances if the hub does not refresh account state.
When news changes the default
Prop-firm rule updates and broker margin changes often push operators from "copy 1:1 lots" to proportional or capped risk. Revisit the rule when account sizes diverge — not only when the strategy changes.
Soft next step
Try the free copy ratio calculator, then the risk lot size calculator. Neither replaces broker specs or firm rules.