pretty sure the answer is "no" but can a map service have more than 1 time-aware layer? if so, how can you tell the map's time slider which layer to "slide"? and what happens if you mix layers with different time intervals, say one in years (road construction project stages) & hours (turbidity model in & around construction site)?
Absolutely you have have more than one layer with time enabled.
To tell the TimeSlider which layer to work with you have to set the timeSlider.createTimeStopsByTimeInterval and the values for that function will come from the layer that you want to slide.
var timeInfo:TimeInfo;
timeInfo = (layer as ArcGISDynamicMapServiceLayer).timeInfo;
timeSlider.createTimeStopsByTimeInterval(timeInfo.timeExtent, timeInfo.timeInterval, imeInfo.timeIntervalUnits);
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