But if my Fi methods are clearly inadequate or inappropriate for the situation, then it may be time for a "reality check." It should be a given that my Fi isn't automatically the best way to address every situation; my Fi may simply be the wrong tool, or my Fi may be working with outdated values and information because it hasn't been keeping up with changes occurring in my life (new job, new relationship, new responsibilities, etc.)
On the topic of values, rules and principles (in effect, all judging functions: Te, Fi, Fe, Ti):
For myself, I’ve adopted the mindset of using and doing what works for me. And you’re right, one function does not meet all my needs, achieve all my ends, or make me dynamic and adaptive. Different situations call for different behavior, and if you’re always trying to behave according to one set of values and principles, you’re going to find yourself running into conflict on pretty much a daily, if not hourly, basis.
My Fi certainly has some values, but I’ve found I need to shed them like a skin in certain situations, not because I’m weak and can’t hold onto them, but because I know it helps me to stand outside myself and consider what would actually be the most adaptive and useful approach to a given situation. I always try to consider what would actually work for me, rather than what is simply congruent with my values and principles. Fi-dom types tend to fall back on their values in every circumstance, treating them like the compass by which to navigate the mysterious and confusing world of decision-making; it’s a common theme among them that congruence is the key to a healthy and happy life. But I know that the values and principles I've learned will not work best for me in every situation, and that congruence for congruence’s sake usually leads me to form debilitating habits and mindsets; it closes of possibilities and closes off adaptation. It’s like holding yourself to a rule for the sake of holding yourself to a rule. NO rule governing human behavior is applicable to all situations, and often there are much better options available and much better tools for getting the job done. (It's similar to what Athenian seemed to be doing in the thread about whether Dana should be banned or not; she was stubbornly insisting that the rules should apply in every situation, but Jennifer kindly pointed out that rules are not meant to enforce themselves, but rather they are meant to protect and aid people, which means they're somewhat flexible.)
It’s not just values that cause stress. It’s also principles, which work under a similar theme of congruence. If I wanted to operate on the principle of efficiency (Te) all the time, I’d bring myself a lot of psychological pain, just as much as if I wanted to operate according to a particularly value, say, kindness, all the time. With efficiency as a guiding principle for behavior, I might run the risk of constantly feeling inefficient and underproductive; I might stress myself to accomplish the most I possibly could in a day, thus wearing myself out.
One of my best INTJ friends does this; it’s one of the most consistent themes of her life, and it’s one of her greatest areas of concern and stress. Her journal is filled with powerful laments regarding how unproductive she feels; it’s common to see her write self-deprecating and bitter poetry about it. I’m guessing that’s a result of her depending too much on Te as a principle. Also, her tertiary (“third-rung”) Fi probably stubbornly reinforces the principle arbitrarily, saying, “Come on now, keep being productive! You’re on the right track, I know it! Keep it up!”
But again, adhering to a rule in all situations for the sake of adhering to a rule is maladaptive. We all try to form these guiding lights for ourselves, but the simple truth of the matter is that almost no rule whatsoever, no matter how awesome it sounds, and no matter how well it works for you in some situations, will work for you in all situations. Honesty, for example, is something so many people are proud to adhere to, but you’d be lying to yourself (har har) if you thought it always yielded you the best results possible and made your life easier in every circumstance.
So I treat things like this: either they work in a given situation, or they don't. If they don't, I know not to use them in similar situations, but rather to try something new next time and see how well that works instead, until I find something that yields me the results I want. I've given up trying to force my values and principles on every situation. I've given up trying to see situations as being governed by values and principles. What matters to me is what works for me, and congruence is only useful to me inasmuch as it is, well, useful; that is, congruence is something I adhere to in situations where congruence yields the results I want. For example, if I'm a teacher, I'm probably going to try to adhere to certain rules just so my students always know what I expect of them. In that case, consistency is probably useful, both to me and the people around me. But congruence isn't always useful. For example, if I consider rules simply as tools to protect and aid people (i.e., if I consider people as the purpose of rules, thus more important than the rules themselves), I'm probably going to listen to the story of a student who missed the final exam rather than failing him/her outright. I have to carefully weigh the pros and cons of my actions: if I make an exception for this student, that means I'm not 100% congruent, but I also want to be compassionate, and I want to serve my students rather than simply dictate to them.
My Fi is inherently opposed to this: What?! The same principle doesn't work in every situation? The simple answer is: Nope.