Out of the stuff you "regularly" wear, how many combos of
do you have?
So I typically rotate through 3 beanies, 2 pants, and 2 jackets = 12 potential outerwear combinations.
Now take the number of days per season you typically get in, for me it's around 24 days / season, and divide it by your combos, and you now have
24 / 12 = 2.
It's going to be 36 C today, so I couldn't think of anything better to post.