A sign of an experienced operator in any organization is that the person knows which battles are worth fighting. The inexperienced individual jumps on a horse, rides off in all directions, and in no time is exhausted, disliked, and disoriented.
Cautiously picking your battles is wise because organizations are conflict-adverse and enemies accumulate. The person who is crossing you this week may be needed as an ally a month or two in the future and upper management begins to wonder about any person who does not play well with others.
A battle that is well-chosen is one that reasonable people would expect you to fight. Failing to fight one of those can diminish your clout and reputation. That makes it worth your time and energy. There are, however, few of those in most careers. Each time one is fought, it should be quickly followed by a review of how it might have been avoided for few battles are waged without casualties on both sides and some are ended without any obvious victor.