Worldbuilding Pro Tip: Counter Culture and Exceptions are just as important as whatever you develop for your world
# Definitions First, let me define what "counter culture" and "exception" mean in this situation, I'll start with the latter first.
Very often in society, there will be situations where there is a cultural or situational norm. This can be everything from gender roles to military formations to children's games. These exist *generally* but are not exclusively the case.
An *exception* is just an instance of this convention not being the case. Sometimes men stay at home and take care of the kids, sometimes military formations break and they need to reconfigure on the fly, and sometimes kids change the rules of game to be more fun, or just be spiteful.
Now, as for Counter Culture, this is something a little more involved. It has been seen across every society across all of human history that there has been a standard "culture" and a "counter culture". The former being what society generally wants, and the latter being what society generally allows to break.
This is not an optional feature, at least if you're genuinely trying to be authentic and make a living and breathing society in your world. By all means ignore the counter culture if your goal is exploration in worldbuilding. But do know that if you want to find new angles to build your world, rebellion against society is just as ripe for development as society itself.
# Examples
Alright, with that said, let me explain what I mean about they being just as important. I'm sure we've all seen, created, or experienced some form of worldbuilding moment where we see how the rules of society work. I don't mean hard features like the physics of magic or how an alien species works biologically, I mean the soft stuff like cultural trends, fashion, politics, and everything you'd expect to read about in a magazine or documentary. Stuff that *changes*.
If your setting has a culture where women wear makeup in a certain way with age, there *WILL* be women among them who "break" the rules. Some young women will wear the style of an older woman as a statement, while some older women will do the reverse as a protest against being called "Old". Some will refuse to wear the makeup style at all and mix and match features, others might just refuse to wear make up at all. This is an example of culture as medium. Some people play with the ideas to show individualism.
Another example, lets say your warriors use scars on their arm as mark of battlefield prowess. If they get that scar during a fight, is that more or less impressive then adding it after the fact? Would a superior officer manually add new scars to inflate their status, what if they got a scar from something non-combat related? Even if you use the honor system and generalize, this is still something to consider. This is an example of culture by mistake, you can't culturally account for individual exceptions.
# The Point Everything I've said until now has been in service to a point a lot of newer worldbuilders miss when developing their worlds. If your goal is to make an interesting and lived in world, the kind that people could see themselves in, then you need to account for the nature of people. Not just humans, but any alien/fantasy race. Humans will rebel against somethings, and cow people would rebel against others, and space rock people would rebel against even others.
Don't just say "People in my world do X for Y reason", also state "People in my world who don't do X avoid it for Y reason". You'll find that often, exceptions are more interesting then the norm.
# "But what if I don't want to?"
This is perfectly fine, I'm not trying to be the end all be all master of what is and isn't good worldbuilding, my goal here is to point out that rules are broken as often as followed, and if you want that edge to make it feel even more real, show what rule breakers do instead. People and places at the extremes of society is often where change comes from, and if you give thought to those places, you'll discover new things to explore.
Even if you don't want to develop the entire counterculture for your world's culture, just ask yourself a few questions and you'll find some interesting things to consider:
* Who doesn't do this? Why? * Who pretends to be normal, and how do they show that? Do they? * Who rejects it? * Why do they agree? Do they completely Agree? * Who benefits from this being "normal"?