So I think what happens, and what I had a tendency to do was to have a bet each way. In front of the class I would explain the rule and then go on to spend almost as long trying to justify why you should use the rule while always using language that accommodates the occasional breaking of the rule. At the very least we choose words that don't remove the possibility of breaking the rule (I am generalising here I know).
You see as teachers in creative fields tend to be creative themselves they have usually devoted some of their time to “sticking it to da man”, and now they don't want to become “da man”, and often with good cause. Your teachers were young themselves at some point and they know that when people tended to force rules upon them at a students age their natural reaction was to resist or push back ( I.e. sticking it to da man). We have special, almost cliché ways of trying to get the the rules across without seeming like “da man”, the most often used being that old chestnut that, “you have to know the rules before you break them.” Note that its not about IF you break them but WHEN.
My concern is that this leaves the door open, it creates an expectation that there will be a time when you can choose to break the rules as you wish, or that there is flexibility in how diligently you should apply the rules. Often after I had explained a new animation principle to my class they would be sent off to do an animation exercise designed to get them implementing the new information. Then when I came to look at the animation for the first time they would hit me with a, “Yeah but I wanted it to be like this so I didn't think feel like using the principle there.” Or even worse some would hit me with some kind of ultimatum, “I can't apply the rule and do this at the same time.” This is on their very first scene since being taught the rule, doing an exercise designed so that they can practice the rule, and they think they have stumbled across the exception to the rule already. I suspect that I as the teacher have unintentionally pointed them in that direction, the door has been left open. I've been working in and around animation for over a decade and I can count on the fingers of one hand the amount of times I have intentionally broken an animation principle for commercial work, and when it did happen I didn't plan for it, it only happened after I had explored every other avenue and possibility that involved using the rules.
Now I want to make it clear that I am not talking about experimental work, obviously that is about testing the rules and assumptions we make when thinking about animation. Even as I typed that last sentence however I realise I'm providing you with another cop out avenue. If you set out from the beginning to make an experimental piece then that's great, but be honest with yourself, did you plan to break the rules or did it just kind of happen? If you are a student, let your teacher know its experimental before you start so everyone knows where they stand. If you are going to flip flop between the two depending on weather you can be bothered applying the rules then you are not going to end up with a very good experimental piece or a very good commercial piece, what's the good in that?
I think a good animation course (like the one I was a part of) will have specific time set aside to experiment with the medium. It helps students to see beyond the mainstream commercial animation they probably spent most of their childhood immersed in. The lessons learned there may not make for great show reel content, but add to the texture and resourcefulness a student can take with them into the workforce. Believe it or not, once they are assured you have a strong understanding of the principles of animation and can apply them at will, employers are looking for staff who can bring new and different perspectives to the workplace. But you will never get past the front door and have a chance to impress with your creativity if you don't know the rules and have proof that you can apply them.
Aside from not understanding yet I can think of two motivations that might be affecting the student when they are trying to dodge the rule. One might be that they just don't feel that they could be bothered implementing the rule. If this is happening to you consistently then its a real bad sign I'm afraid. People who don't dot their I's and cross their T's don't succeed in animation, its as simple as that. Its consider a different career time.
The second and more common reason (I hope) that I suspect is more just a youthful or new perspective on the craft, a willingness to test the limits of these “so called” rules (as I have sugested, perhaps encouraged by the teacher). If this is the case then I suppose it is inevitable to a degree, but maybe I can give you some food for thought that will help you to refocus that energy.
Lets consider a parallel career, that of an Author. There are books that have literally changed the world, and yet all of these books are based on an underlying language, the language is mostly set and inflexible, and yet the writers use it to communicate every possible kind of idea and emotion, even rebellious ones.
Without the language, the whole thing falls to pieces. Imagine if this blog post had been random gibberish up until this point (hopefully it hasn't really been :), do you think you would still be patiently reading through the lines of text by this stage. What if I followed most of the rules of the language, but ignored the ones I thought were too much trouble. Lets say the sounds that made by combining two letters like “th”, “ch” and “sh”. What if I just put what ever I felt like in those spaces and left it up to you to work out how the word should be said? It might be novel for a little while, but it sure would get tired fast. Now imagine if everyone writing in the world picked and chose from the rules as they wrote for their own personal reasons, every new thing you had to read from street signs to Harry Potter would become a new riddle. A riddle that stands between you and an understanding of what meaning the artist is trying to communicate.
What I'm getting at is that the rules are your friends, they empower you to reach and connect with your audience. As a student or junior animator, your passion and obsession should be about leaning, applying and practising the rules, not looking for ways around them. The rules or principles were not made up by some oppressive dude, they are based on observations of nature, is that really where you want to focus your rebellion? I'm not asking you to become a robot, I've never met an animator who's work doesn't communicate something about their personality, it just happens that way. Have some faith in yourself, use the rules and bend them to your will, your work can still be unique.
If you are willing to sacrifice your knowledge of the rules in order to express yourself then you may just be throwing away a whole lifetime of creativity ans self expression. Think of the audience you might reach through a whole career of animating, the thousands of people you might be able to connect with, to share your message with. Consider how you might use the craft to draw the viewers in, make them feel something about your subject matter. It could be something silly or serious, the principle is the same. Now compare that to the amount of impact you might make in the world with a few years of student animation (that doesn't even successfully apply the principles of animation) followed by a lifetime of flipping burgers or stacking shelves.
So the question is simple, why are you studying? For a short term experience or a life time of creativity? Obviously the answer can not be black and white (although I know students who try to make it so), but maybe its worth a little reflective time asking yourself where you want to fit in there, and how you can amend your behaviour as a student to make it happen.