When I first cruised
DCL back in the dark ages shorts were never allowed in the MDR. Formal Eve was full of folks in long gowns and tux. Palo did not allow jeans and men had to wear ties and jackets.
I actually loved it. It was my once a year opportunity to wear clothes that I would never wear at home, and I have to take two flights and pay for a hold bag to accommodate this.
However, DCL have now basically done away with any dress code whatsoever everywhere, so no holed jeans in Palo the last time I was there meant that some diners wore frayed holed dirty jeans with T’s and runners and weren’t turned away. Short shorts are worn in the MDR’s and some people just wore cruise casual like that on formal night.
So the answer to this question is wear whatever you want whenever you want to wherever you want. DCL don’t appear to mind.
I’m going to buck the trend by doing what I want too so I still bring out my long beaded, sequinned gowns for formal night, cocktail dresses for semi formal or dress up night, and dressy dresses for Palo. For me that’s part of my cruise experience just as much as cruise casual is for others.
Do what works for you.