Watch ergonomics isn't about generic comfort: it's about the physical relationship between case, wrist, and intended use. It's a design discipline, and you see it in construction choices, not marketing claims.
The case is where we start. A cintrée case—curved at the sides, like Cartier's Tank Cintrée—sits on the wrist differently than a flat case: it distributes contact surface along the natural curve of the carpus. The same principle applies to lugs. So-called floating lugs, which remain partially detached from the case, absorb the wrist's micro-movements without transmitting them rigidly to the case itself. Articulated lugs go further: they move actively, which matters on diameters over 42 mm, where rigidity hurts after a few hours. The rotating tubular lugs on certain concept prototypes allow controlled angular excursions that reduce lateral tension during movement.
The crown is the second critical issue. On the right wrist, a crown at 3 o'clock contacts skin every time you flex the carpus. Moving it to 9 o'clock—a typical choice on dive watches for right-handers, where the term describes exactly this configuration—eliminates the problem. Moving it to the caseback, as Ressence did, also solves the question of the case's visual symmetry. A crown at 2 o'clock, slightly off-center, is a functional compromise: it reduces friction without distorting dial readability. The retractable crown patented by some contemporary makers eliminates the issue when the watch isn't being adjusted.
Perceived thickness is its own chapter. Concave profiles on the caseback or bezel optically and tactilely reduce mass, even when the actual millimeters don't change. Tapered bracelets—wider near the case, narrower toward the buckle—shift weight toward the center of the wrist, improving balance. The ceramic bracelet on the Bathyscaphe is a relevant technical case: links of variable geometry, cam-action pins, progressive tapering. That's not aesthetics; that's load-distribution engineering.
Finally, rapid legibility is cognitive ergonomics. The relative position of day, date, and month on a perpetual calendar isn't a style question: it affects the time needed to decode information at a glance. From the bench, I've seen too many watches with dial layouts designed for photography, not for reading on the fly.