After experiencing several highly stressful jobs, I came to an important conclusion: That while choosing the right job is important, it's even more important to know when to leave it. My suggestions follow.
Quit your job, if you have the economic freedom to do so, of course:
(1) When the political infighting has become intolerable. This is an individual matter since what one person considers intolerable, another person can ignore.
(2) When you're developing psychosomatic symptom such as stomach distress or neck pain. During one job, I accurately interpreted my neck pain, which I had never experienced previously, as reflecting several of my employees being "a pain in the neck."
(3) Leave a job when your boss wants you to stay. If remaining too long, you'll be viewed not as you were initially, part of the solution, but as part of the problem.
(4) Leave the job on friendly terms. You'll later regret speaking harshly. Also, if a job was really bad, you had to have been dumb to take it so that doesn't say much about you, does it? (Disclaimer: I've been dumb.)