When Mary Lee and I were first married, along with a couple other odd jobs I served as custodian of Covenant Presbyterian Church in Madison (no, we didn't attend). This meant clearing the snow from the walkways and sidewalks after every snowfall. Covenant sits on a corner lot and has very long sidewalks.
Those winters were some of the harshest on record in Wisconsin... so I quickly learned that the time to clear the snow is right away, before anyone walks on it. The dummies who wait are left doing what this man does a good job describing and warning against.
Which is why my own driveway is loaded down with thick ice right now.