Well, as of now it takes about 48 hours of solid cold (like lower 20s) to put down two feet on Northface. That's 1 foot/day. So 10 days I guess. This year Northface got 4 full days of snowmaking. You could do it on Plunge too, but for it to be effective, you would have to install more guns and pipe. On the lower half.
I'll take boilerplate ice over wet snow any day