Early in United States history, there were disagreements about what should be the length of a Presidential term. A single six year term has been suggested throughout the course of time, but eight years, divided in two terms ultimately won out.
How plausible, and what effects, would a different set of terms be on the United States. What if the United States chose to elect a President for a single nine year term, but a snap/recall election could be called either in the third year, or the sixth year of service? Not both, meaning that if Congress decides to call a snap election three years into the President's term, they cannot call for another in the sixth year of the term (should the President successfully keep the office). Just to be clear, a President who successfully defends their term does not win another nine year term. They are simply granted a continuation of their term. If an incumbent happens to be defeated in a snap election, his/her successor gets a single nine year term, which can see a snap election called either in the third year or sixth year as well. So on and so forth. A defeated ex-President cannot run for reelection. Snap elections are not mandatory, but with this system I can only see so very few Presidencies not being challenged.