Yeah, don't forget about the oil ports... They do work.

Anyhow, back to the OP. It actually isn't normal for a NR equipped bike to start squeaking a third of the way into a century, even in the rain. What grease were you using? Perhaps you could use more of it. All campy NR bearings can be completely packed and oozing grease, not a problem. A lot of people used the tube slice around the bottom of the HS trick during the winter. It works well. Might reduce your no hands riding ability a bit. I've been using Finish Line Wet lube for the chain during the winter. Seems to stay on well in the rain.

I guess it could also be your local road conditions. I'd imagine types of road grit vary by location.