Why is always that crucial? If a unidirectional bezel is knocked and accidentally moved on the dive, it could only Exhibit a longer underwater time. Which means the wearer will overestimate as opposed to undervalue immersion time, and in cases that need decompression stops, this can be a make-it-or-split-it issue https://www.watchesworld.com/frozen-in-time-luxury-watches-for-winter/