The simulator is seeded: the "random" return paths are generated from a fixed starting point, so running the same plan twice gives exactly the same numbers.
That is deliberate, and it buys three things:
- Fair comparisons. When you change one input, or when an optimizer sweeps a whole grid of candidates, every variant is judged against the same set of market paths. A difference in the result is caused by your change, never by a luckier draw.
- Reproducibility. A success rate you saw yesterday is still there today. Results are testable, and a saved scenario re-opens to the numbers you remember.
- Hand-checking. With every volatility set to zero the fan collapses to a single deterministic path you can reconcile line by line in the year-by-year detail table. The Trace: zero volatility button on that table does it in one click. It zeroes Blended's Volatility %, the three per-asset vol fields, and the two uncertainty toggles, and Restore volatility puts your exact settings back.
The trade-off: a seeded run understates "simulation noise," the tiny wobble you'd see between two genuinely random batches. With 1,000 paths that wobble is small, and stable comparisons are worth far more to a planning tool than fresh dice each run.