I've tried to answer your question on whether it is the usual/common or uncommon thing to wear layered clothing in cold countries or not.
IF you're talking style and fashion then I'll share with you my observation that people with a personal style(whether or not others may find agreeable) does not follow the fashion. Style goes with personality -- the person is more important than the clothes he/she wears. A person who follows the fashion keenly usually does not understand style because personal indentity if that person has one is lost and we call that a fashion victim.
Style develops over time, fashion goes on a whim.
Actually I didn't ask this question. But yes, certainly it is more important to layer in a cold country.
And as for personal style, I can be into a techno, futuristic aesthetic- Y3, for example- and still move with the 'fashion' within this genre. Similarly if I want classic American (CK, Levi's), urban/modern (Apple, Fuji Water, etc), and so on, ideas still change within this genre.
Only a very few people follow 'trendy' fashion, for which the key thing is constant change- the H&M and Zara crowd, as well as other fashion-forward labels. But BTW, it doesn't change on a whim. These designers follow rules like 1) has black/ white been 'in' for too long? Are people's wardrobes lacking color? 2) What is catching on around the world, in India, Thailand, Greece, Japan, and so on, that others might like to wear?
It's not simply a designer sitting around and pulling ideas off the top of his head. Fashion changes, but not 'on a whim'.
My point? If you don't layer, that's your choice, with key consideration to what you consider to be practical. But it's not really a style. In almost every style (other than 'uniforms' like what uni students wear: T-shirt and berms; or office worker's shirt and trousers), layering exists. Sometimes you layer a scarf. Sometimes you layer a vest. Sometimes you wear a singlet and layer over with a shirt. But layering is just a tool. Just walk to the shopping mall and look at ANY brand, covering every style imaginable. 99% of them would have displayed mannequins with layered clothes at some point of time.