Title says it: what's your criteria to decide whether your time managing a club is over?

Do you get "political" with the board over denied requests, set specific targets in terms of trophies, etc? Or are you a one-club manager and spend your whole save at one club?

Also, what type of career do you prefer and how does it influence your future decisions? eg, I enjoy taking charge of smaller clubs (don't mind a second division, nothing further though) and give myself a 5 year limit to win the Champions League. Once I achieve that, or run out of time, I resign and look for new opportunities. It'd be interesting (for me, at least) to compare different approaches and philosophies, it gives the game depth and might inspire some people to try something different.