RE: Beginner glossary Q&A: complication, caliber, jewel count, power reserve · RWI-12386

Power reserve is how long the watch runs from full wind until it stops. It matters if you rotate watches: a 38-hour reserve may stop over a weekend off the wrist, while 70-plus hours may not. One clarifying point is that rate stability often gets worse near the end of the reserve, so the full figure is not all precision-grade running time.