I can visualize this, but I didn't notice any difference when I started running full fenders. I rode fenderless for years, and once the snow was deep enough, the cassette would eventually cake solid. I could never watch it happening (it's difficult to watch your rear hub while riding for an extended length of time ), but I assumed that the caking was from snow kicked up by the tires. My solution was to switch to an IGH.

Maybe it happens faster with fenders? Like I said, I never noticed a difference. I don't run fenders because of snow, since all it really does is keep snow off of my shins and shoes; but I'm too lazy to remove the fenders for the winter, and it's nice to have them for the occasional warm and wet weather events that've become increasingly common. Come spring there's no way I'd ride fenderless, as this whole town turns into one big slush puddle for two weeks while the winter snows melt.