The notion is from analog dive watches; the bezel can be used either to show elapsed time (by setting it to start at zero), or to show time remaining (by setting it to start at 60 minus dive duration). This makes it a visual count down: you look and see how far the minute hand has to go until it reaches the red zero marker on the bezel.
If you want to complete a dive in 50 minutes, you rotate the bezel (with the red marker on it) back 10 minutes, thus making it 50 minutes until the minute hand reaches the red zero marker on the bezel, and thus the digital count up starts from 10 minutes instead of zero.
It is like the unidirectional bezel on the Rolex Submariner, where rotation of the bezel can only shorten the dive time, never increase it, for safety. Thus if the bezel is rotated, it starts the count-up from a positive value (in effect artificially increasing the elapsed time and hence decreasing the dive time).
This watch face is not intended to be an efficient way to display timer information (for which a digital timer would obviously be most efficient), it is intended to echo classic analog watch faces and how they were used with a bezel to visually display timer information.
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