If it is to go out with the same friends about 2 weeks but with different friends then it doesn't matter

Or if it is with a boyfriend then about a wekk as well depending on how much he actually is aware of clothing!

As long as my clothes are clean and in good repair, I don't really pay attention to how often I wear things. I tend to splurge on things I enjoy, and do not have that many outfits. I DO have things that I can mix and match, so I do that, but more often than not, I'll wear my current favorite frequently.
In the winter here, it doesn't really matter because I'll always be wearing a long skirt or jeans, shoes, and at least one jacket covering up whatever top I'm wearing.

Then again, I'm a college student and can get away with that. If I worked in an office, I'd probably stick to only wearing the same thing once or twice a week, depending.