I have a somewhat different opinion. Our snow will change from very very dry to semi wet depending on the elevation alot.
In dry dry snow, its kind of like sand. You need some wheel speed to keep forward momentum going, but if you start digging you back off immediately.
On the wetter stuff or something that has a crust, slow as you go. Creep and let it pack or try to stay on top of it.
Most of our snow is like wheeling in granulated sugar, it doesn't pack well and it takes 4 rigs to get a really good track going through it. It also requires a bit of wheel speed.
Even on the wetter snow I have used wheel speed to keep going. Snow is such a dynamic terrain that it really truly depends on how the snow is.
So ummmm to answer your question both
But your pics looks like the snow was packing so I would say low and creep and let it pack