200 trades should be ok for 2 DOF, so the WFO period is good. Re-optimization should happen in the same time interval as the WFO test period. It can happen that a system does not work on old data, due to the change of markets. For the same reason, very long simulation periods, such as 15 or 25 years, make not much sense. The lifetime of a system is normally in the 5 years range.