Insulate when doing repairs
It is always a good time to up insulation. My house has a utility room, same slab as garage, it is a pass thru between garage and kitchen. When the house was built, they thought they should insulate the wall between the utility room and the garage, with no insulation between the cold, large utility room and the kitchen and downstairs bathroom.
A couple years ago, I replaced the, broken plastic shower in that bathroom, and then it turned out I had to replace all the house plumbing. That means the walls were open. More walls, due to the plumbing issue.