You want a margin of error in a system that shouldn’t have any, right? A flight plan that’s “just right” means every leg is trimmed to a microsecond, every speed change to a single foot‑per‑second. Instinct is useful, but it’s a fuzzy variable that wrecks the audit trail. If you really need a sweet spot, tighten the constraints until the GPS and the pilot are locked into the same metric, then you can let the instinct handle the only thing the GPS can’t predict—an unplanned turbulence event. That’s the only place where you’ll get a “satisfying” deviation.