How often to wash clothing types

I was reading some articles on how often to wash specific types of clothing. Different people have different frequencies.



One question no one discussed, was how to keep track of how many times you've worn your dress shirts (for example)? Say you want to wash them at least every 3 wears, are they putting stickers on their dress shirts after each wear?



This made me think of a good math problem, coming up with the optimum frequency given cost in $ and time and the fact that washing/drying typically ages clothes.....

How often to wash clothing types