I absolutely track number of wears and CPW for every item in my wardrobe (including all accessories), except underpinnings and socks. I've done this for years and the data is valuable to me.
I have a different CPW goal for different categories (e.g., pennies for loungewear; $3 for tops; $2 for pants; $7 for some specialized sports wear). I have a small wardrobe so these goals are achievable.
Because my wardrobe is categorized in a spreadsheet I can easily see if certain categories are becoming inflated. In fact, that is exactly why I put all this information into a spreadsheet. Prior to YLF, I overbought certain garment categories and underbought others. That led to a lopsided wardrobe. Getting dressed in the morning was hard-to-impossible. It forced me to stop buying the "easy" pieces and focus on buying the "challenging" pieces. I don't know if I could have transitioned without hard numbers to force the issue.
The data also resulted in "spending caps." If I have a defined goal for CPW and I already know how much wear I can expect from a garment category based on history, it is easy to calculate the upper limits of what I should pay. I put those spending caps in writing so they are locked in my brain. The caps are not firm. I find I exceed them for pants and tops at least once per season. This is allowable .... but I limit them on a seasonal basis. The spending caps also change, depending of annual goals.
I do not count number of wears with the goal of reaching the magic number of 30. That thinking evokes the idea that once 30 wears is reached, permission has been granted to move the clothing item on so something new can be bought in its place. I expect far more than 30 wears. My wardrobe is small and I do not need a lot of variety. I focus on buying quality items that can be worn often and over the course of several years. I do not see clothing as disposable.
I do not track the percentage of items worn. I assume that my entire wardrobe is worn ..... but you have a point. Certain garments are favored. They get worn all the time. When I see this happening I do two things. One, I make it a point to pull the lesser worn items forward in the wardrobe so they are in rotation. Two, I examine the favored item to figure out why it is so loved. Usually in my case it comes down to the quality and feel of the fabric against my skin. Or the fit.
If I find that some items just are not being worn .... for whatever reason, I have the data I need to purge it. Thirty wears or not. It did not work for me. It could be fit. It could be poor proportions. The garment was a fail for my wardrobe. Gone.
I admit my method is counter to how Angie shops. But our lives are lives and goals are very different. I can't help but think that if I shopped emotionally, I would have a severely skewed wardrobe of gorgeous and prized items, but I would be unable to get dressed in the morning and I certainly would not be able to dress for my individual roles (e.g., work, casual, athletic).
My spreadsheet forces me to be honest with myself. It limits (does not prevent) bloat. Oh! That is another thing. My spreadsheet helps me evaluate just how many items in a given category is reasonable! It is easy to see when I start overbuying! It forces me to stop and think about it because some thought process is moving me in that direction. I try to decide if it is reasonable or not.
So there you have it. Valuable for me. Burdensome for some others. It depends on how your brain thinks and what your ultimate goals are.
Good luck.