I have a very old Chronos, with a switch on the bottom, so I don’t know for sure, but I think on the switchless models AN-1 functions as follows:
With 10 (or more) seconds of delay remaining, the delay time is displayed as 2 digits, and the main time displays as h:mm if 10 minutes or more, m:ss if less than 10 minutes.
With 1 to 9 seconds of delay remaining, the delay time is displayed as 1 digit, and the main time displays as h:mm if 1 hour or more, mm:ss if less than 1 hour.
Once the delay time expires (0 seconds), the main time displays fully as h:mm:ss.
You’ll have to ask somebody who has a newer model (and I’m curious too, so would somebody please let us both know?) but I suspect it would do as you suggest.
And that’s not so bad. If the remaining main time is, say, 28:47, I would prefer to see the display switch from “10 - 0:28” to “9 - 28:47” rather than to “9 - 0:28”.
This could mean, I’ll admit, that some players might find a 10-second delay more disconcerting than either 9 seconds or 11 seconds. With 9, you don’t have the problem. With 11, at least the display would remain in one format for a full 2 seconds rather than 1.