Other times, where the snow is simply super abrasive, I would go with multiple layers of LF Blue followed with a final layer of LF Blue/XCold mix. The snow/air temps and humidity could be identical to the Birkie day, but the snow might be different.
Basically, when the snow is abrasive and cold creating big dry friction problems, go with the multiple layers of LF Blue followed with a final layer of LF Blue/Xcold. (By the way, LF Blue is harder than System 3 Blue). When it is not like that, go with the HF Blue covered by the rotocorked JetStream Moly.