I mean if they are just seen in the background I would just create a certain amount of different background characters so each time you can place different ones and don’t have to change their outfits. I think as long as you don’t always put the same ones you don’t need to change their outfits and I’m sure there are plenty of people that don’t care about that so really it is up to you if you want to put in the effort or not.
Here is a school uniform idea just in case.
