Ground that happily carried your base plates in September behaves very differently after a hard frost and a thaw.
Settlement after a thaw
Frozen ground is stiff. When it thaws, it can soften well below its original bearing capacity, and a scaffold that was plumb in December can be out of level by February. Sole boards spread the load; regular inspection catches the movement.
Ice, not just wind
Boarded lifts hold ice, and ice adds load and makes decks lethal. Winter inspections take longer for a reason, and gritting the access towers is part of the job, not an extra.
