I bet your right, Waumbek...
There (unfortunately) isn't much question in my mind that different district crews have very different levels of ability to keep roads clear. There are portions of 93 from Exit 28 south where you can pretty much count on the road being scraped and well maintained, almost regardless of how hard the snow is falling -- and there are sections where you're almost guaranteed it will be treacherous, even in moderate snow events. As you drive along and pass from zone to zone (you know when you pass into a new district, because the plows turn around at the crossovers), you can't help but wonder why the variations are so noticeable.
I guess slapping a 40mph speed limit across the board at least reduces the probability someone will lose control or slide into another vehicle.