I prefer using the same outfit, partly because it's easier but also because it makes the character more recognizable. But if there's a reason for changing outfit (going to a party, having to use a uniform etc) then I think it's fun to change it up. Or if your story is focused more on fashion, varying the outfits often is nice.
But when you think about it, it's kinda weird when the characters are wearing the same thing everyday. Do they have multiple of the same outfit, do they have to do laundry every day, or smell real bad?