Expressions become dated. In the field of clothing “Casual Friday” is an example. The expression makes little sense today, since all days are casual days in 2017.
Ten years ago the situation was different. You could be in suits Monday until Thursday, and then on Friday you would dress down in a sport coat or a knit jumper, so you could leave early for the countryside.
All that is generally speaking, of course. Yet there has been a shift in dressing towards more informality, hasn’t there?
The suit is still there, fortunately. Shirt and tie as well. Those garments are less mandatory garments nowadays though.
I think young men, who are interested in suit and sport coat, are less preoccupied with “the rules” than 10 or 15 years ago. The sartorial world of Publius Decius Mus is crumbling.
What counts today is looking good and SoMe likes, which is okay, and a tiny bit disturbing, because indifference can be a henchman.
Leaving aside consideration on style changes, here’s my Casual Friday attire. I’m sure many workplaces would deny me access in that style. Not because it’s too formal or too casual but because it is too flamboyant. Green, orange and light grey trousers are not common enough. The attire will break dress codes. I like the style though. I feel it fits me. That is important.