The time on a digital clock, for me, changes whenever I look away and back again. Sometimes if I look at it for a few moments, the time will even change in front of me - usually consecutively as well. For instance, it would be at 8:55, then change to 8:56, then 8:57.

It has only failed me once, but that's enough reason to not rely solely on the clock RC.

Like you Loaf, I usually do the nose-pinch, then look at my hands, then a clock if there's one around.