custom Lifecycle funds starts with the real TSP record, turns each candidate G/F/C/S/I mix into a monthly rebalanced series, and looks for earlier windows that behaved like the current setup.
The recommendation is then screened against the Lifecycle funds that were actually available at the same anchor date, so the final comparison stays tied to a real federal employee decision set.
The engine starts with the real TSP record. It looks for earlier market windows that resembled today, tests many possible custom G/F/C/S/I mixes, and leans on the mix families that held up best in repeated benchmark runs.
Every comparison uses the Lifecycle options that were actually available at that time, not a hindsight winner selected after the fact. That keeps the headline evidence tied to a decision a federal employee could realistically have made.
Once the member saves a baseline mix, the workspace tracks the starting portfolio, the accepted recommendation, and the Lifecycle menu from that same date forward, so later comparisons do not shift the starting line.