WISN daytime splatter at my location is significant, but not insurmountable. Offhand, I don't remember if WISN was on day pattern/power when I heard WVHF, but even if WISN was at 50kw, I could have easily nulled it.
As for the WISN night signal, it's invisible here 98% of the time. I lived for a year (1976-77) in Lake Geneva, WI, about 25 miles north of here. At that location, WISN at night was audible, but not really listenable. As it is, my brother lives about 12 miles southeast of the WISN stick (or should I say "farm"). and the night signal at his house is only fair, at best. When I drive back home, I lose it within about ten minutes.