In watchmaking, the word system has no single meaning: it's a commercial designation that manufacturers apply to very different patented solutions, from how the movement is mounted in the case to how time is displayed. It's worth distinguishing between them, because confusing them leads to incorrect assessments.
The systems that concern movement protection are perhaps the most concrete. Formex's Case Suspension System, introduced with the Essence line in 2018, elastically isolates the movement inside a titanium container: the goal is to reduce the energy transmitted to the gears in case of impact. Armin Strom's Resonance Suspension System instead works in tandem with the Resonance Clutch to maintain stability of the resonance phenomenon between the two balance wheels of the ARF21_ZG caliber: without this mechanical continuity, the two balance wheels would stop influencing each other reciprocally and the chronometric advantage would disappear.
Display systems are a separate chapter. The ROCS (Ressence Orbital Convex System) is the most radical case I know: a patented module that sits between the movement and the dial, driven by the minute hand axis, and replaces the hands with eccentric rotating discs inclined at precise angles — 3° for hours, 4.75° for seconds and day in the base version, 9.75° in the TYPE 9 S75. The discs orbit on the convex dial keeping the indices aligned for reading: technically it's a planetary differential applied to readability, not an optical trick.
Nomos Glashütte's Swing System is instead an anchor escapement developed in-house, regulated in six positions, present across the entire range including the simplest calibers. The radial sunbeam finish on the oscillating plates is a choice consistent with Glashütte's tradition, not an additional technical function.
Among operational protection systems I should mention ZRC's Crown Protection System on the Grands Fonds: it physically prevents you from wearing the watch if the crown is not fully screwed down, eliminating human error before immersion. It's a more effective solution than any instruction in the manual.
Roger Dubuis's Second Braking System acts on the chronograph second hand to reduce rebound at stop: a detail that those who time seriously notice, everyone else ignores.
From my bench I'll add one thing: when a brand calls something a system without published patents and without accessible technical documentation, the term is marketing. I always ask for documentation before explaining it to a customer.