To tuck in or not to tuck in?

Over lettuce wraps at Bonzai Bistro late Friday afternoon, Amy Dearest and Okie Doke lectured me re: the appropriate way to wear a shirt, tucked or untucked. They’re millennials from Portland, which, I’ve heard, is somewhat more stylish than Coeur d’Alene. According to Amy & Okie Doke, you’re not to tuck in shirts worn with jeans, including form fit ones. You only tuck shirts in when they’re worn with dress pants. And Amy Dearest sez, you never ever ever tuck shirts into sweat pants, even when you’re minding your own business walking along the waterfront at noon. What say you?

Question: Tuck in shirts with jeans and other casual wear?