I agree, I wouldn't roll with just one tire. OK, I HAVE occasionally, like if it's a late winter/early spring cold snap and I think there MIGHT be ice. But for most of the winter, I roll with two studded tires. As I said, I ride 4 miles of gravel, it's snow packed down into ice the whole winter (you can't salt gravel roads) and it's hilly, so it's studs on the back or walk most of those 4 miles.
I've never wiped out in 4 years of winter riding IF I had both studded tires on.