Why size decides the structure
Each sub-account needs enough margin to hold its leader's position at the mirrored ratio. Divide a small balance ten ways and each slice is left rounding positions down to minimum sizes — at which point you are no longer mirroring the strategy, you are approximating it badly.
Fees compound the problem. Ten sub-accounts mean ten sets of entries and exits for the same capital base, and on a small balance those costs consume a disproportionate share of any result.
- Position granularity: small slices round to minimum sizes and drift from the leader.
- Margin fragmentation: isolated margin cannot be shared between sub-accounts.
- Cost drag: more parallel strategies mean more round trips on the same capital.