[UAHaerospace]

some of both possibly, as most manufacturers use spray foam to fill areas where wires and plumbing, etc enter the coach, or where there could be air gaps. Owners sometimes do this, too, once they find areas where the factory missed, but their foam is usually the typical 'yellow' foam, whereas most factories use a darker foam.
Use as much as you wish, or feel the need to, as it can't hurt - it gives you both better protection from the cold weather, and protection from many insects and varmints, like mice and chipmunks.