I wear... 3 outfits... well, I only have 3 pairs of pants I wear. I have about 10 t-shirts, but all of them I've made images to iron on myself, and the shirts themselves are all the same, lol.
It's hard to say what is normal... My mom picks up things that she likes if they are on sale, usually, but she has to really really like it. My boyfriend's mom shops compulsively. I have met a lot of people who just like to window shop and look at the latest fashions, but I was never really with them enough to figure out when they'd actually buy things. It was like, I'd see them one week or go with them while they window-shopped, and a few weeks later, they would have something new.
I'd say maybe... once a month, my neighbor gets new clothes, but I don't really see the point if everything she has fits just fine, lol. Either she is getting rid of a lot of stuff and changes her wardrobe that often, or she has a massively large closet to keep all of the additions in.
I've never really spent a ton of time with anyone enough to see what normal shopping routine is like. I've watched people keep buying when they have no money, and some that just keep wearing the same things over and over until they do have the money. I've seen people just not buy new things because the brand or style they like is no longer around, unless they absolutely have to... and I've seen those that go out and keep up with trends a lot...
Considering everyone's situations are different, I think it would be rather hard to figure it out.
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Sorry about the incredibly long post...
"I enjoyed the meetings, too. It was like having friends." -Luna Lovegood