You could probably do an analysis looking at the expected utility in terms of social benefits (people seeing you as well-dressed or fashionable), or performance of the clothing (sports clothing, jeans, work boots), depending on what you wear and do.
In terms of clothing minimalism, it probably depends on your friends and work environment. Many people seem to have multiple similar-looking work outfits, so that they don't have to worry too much about changing their appearance regularly, and others have room to imagine any number of identical items of clothing in the wardrobe at home. Without evidence to the contrary people tend to expect you to have a similar amount of clothing as they themselves do.
A good tactic is to keep a number of discernably unique and stylish clothing items that you do not wear often at all. These can be rotated for social occasions, so that you aren't seen to be wearing the same thing twice in recent succession. This seems to be all most people look for, although it depends on your associates.
Personally I wear whatever seems comfortable and appropriate, making sure to wash most clothing items after one day of use, and thinking about the social implications of being seen wearing whatever I am wearing. The social implication of wearing the same thing for multiple days is that you are dirty and smelly. In my experience as long as you keep clean and presentable, and are seen to have multiple different clothing items, most people don't worry about it, but this may be highly dependant on your local culture.
Regarding things wearing out at the same time - well, even if you use them as evenly as possible there should be more than enough randomness in daily usage to mean things wear out at different times. Even if you buy two identical shirts, they won't get the exact same treatment, leading to an increasing difference in the number of wears before each becomes unusable. (see "Random Walk" problems for an interesting mathematical treatment of a similar concept)
Regarding rotation making things last longer - I think it's fine to think of it as a fixed (but unknowable) number of uses before something wears out. So no matter how you rotate your clothes, each item should have the same base value as it would have otherwise. Thus individual day-to-day changes in clothing (which items are more relevant to the current day's activities) are probably much more important.
One last unmentioned point - clothes sitting at the bottom of a drawer can be easily forgotten. It can be good to upend your drawers every once in a while just to make sure you haven't forgotten any hidden gems. Or, err, moth-eaten horror stories (although it's been a while since this happened to me).
If it's worth saying, but not worth its own post, even in Discussion, it goes here.