I've used those Cardas tracks to help break in several cartridges. One friend's Shelter 901 spent weeks on the damn thing before it started sounding decent.
My TT turns itself off after 45 minutes, so I take that opportunity to brush things off and switch to a different groove. Going several hours in one groove does seem like pushing one's luck. Give that poor groove a break.
I clean my records exactly like you, but there's always some stuff piled up around the stylus after an extended stay in the same groove. Clean the stylus and cantilever thoroughly and you should be okay. A very gentle scrub with a piece cut off a Mr. Clean Magic Eraser (household cleaning product) works wonders for that baked on gunk.
BTW, I'm not sure it's very useful to actually listen to the pink noise. I think most of the breaking in is mechanical, especially if the cartridge is the only new component. I prefer to spare my ears.