I know some bakers swear by unsalted butter because it gives you complete control over the salt level. And technically, they're right.
But after 20+ years in professional kitchens, I've never found the difference to be significant enough to make me keep two different kinds of butter around.
I use salted butter in cookies, cakes, muffins, brownies, cinnamon rolls... pretty much everything.
The amount of salt in modern salted butter is fairly consistent, and my recipes still call for a little added salt.
Could you adjust the recipe slightly if you're using salted butter? Sure.
Do I? Nope.
The cookies still disappear.
The only time I'd really pay close attention is if you're on a sodium-restricted diet or have a medical reason to monitor your salt intake.
Life's too short to make an extra trip to the store for unsalted butter.