Very interesting thread. It makes me happy that I track my wears, because then I can pull up some data and see how I am doing.
I found that I am at 30 wears for a lot of my workhorse items, actually. Many of them are over that, and quite a few are in their 20s. But...most of my wardrobe is about three years old. I realized a while back that for me to feel like I get my money's worth out of my purchases, I need to plan on wearing them for about three years. (Side note: Now I know why I feel so bored with my wardrobe as of late. It's because a lot of what I'm wearing is three years old!)
I agree with a few other posters who said that not everything can hold up to being laundered 30 times. I hate that! It's mostly fading and pilling that get me. And I really don't feel fab wearing a faded top. I should turn my tops inside-out when washing, as suggested on another thread. Jeans are usually OK with fading, but I always turn them inside-out.
Another thing I do when shopping is ask myself, "OK, if you want to average $2 CPW for this item, how many times would you have to wear it, and do you want to wear it that many times? How many years would it take you to wear it that many times?" That can be an eye-opener. It helps me assess how much I truly love the item.
As Krish pointed out, the four-season climate is also definitely a factor. You are limited in how many times you can wear a given item per year. This is one reason why I try to limit my summer shoes (short spring/summer) and try to buy more cold-weather items (long fall/winter).
And you really do have to be careful about buying an item that "steals" wears from another, because then you feel like you have two similar items, both of which struggle to reach the 30-wear mark.