Dad's rule was: below 5 degrees or more than a foot of snow, wake him up. I never figured out how to fudge the temp.
It was a 6-mile route, and I could do it in 35 minutes in the summer if I went all out. Toughest bike I ever had.
I walked the heavy snow days, got blisters in those boots, of course. Took my time, because a foot of snow meant no school that day, and the sooner I got home, the sooner I had to shovel, a fact, which, now that I think of it, my Dad probably figured out when he made his rule, so he could sleep in.
Morning paperboys saw a lot of stuff they'd never see in the daytime. "Cheaters" had nothing on us.