While 不常 (bù cháng) itself doesn't carry deep cultural weight like concepts of `face` or `guanxi`, its usage reflects a certain linguistic precision common in Mandarin. In English, it's common to use hyperbole for effect. Someone might say, “I never go to that part of town,” when they really mean they go very infrequently. In Chinese, while exaggeration exists, using a precise term like 不常 is very common and clear. It's a neutral, factual statement about frequency without the emotional emphasis that “never” or “always” might carry in English. Using 不常 rather than a stronger term like 从来不 (cónglái bù - never) can also be a way of being polite or leaving possibilities open. For example, if asked whether you eat a certain food you dislike, saying “我不常吃” (I don't eat it often) is softer and less final than “我从来不吃” (I never eat it).
不常 is an extremely common adverb in daily spoken Mandarin. It's used to talk about habits, routines, and the frequency of any action.