It seems there is a common pattern. A president who is elected gets a strong advantage toward being reelected, but after 2 terms, the?

country wants a different party in charge. This pattern repeats over and over. 2 terms of Obama (D) followed by (R) Same for Bush II. Same for Clinton Reagan's success I guess broke the pattern for one term, as did Carter's failure. Nixon elected to 2 terms followed by (D) Kennedy elected to 2 terms followed by (R) Eisenhower elected twice followed by (D) This goes all the way back until there were no term limits. So is it that neither party can keep the country happy for long? Is it that once a president is elected, he has an unfair advantage toward reelection? Is it that the desire for change is stronger than the desire to stay in power, so more people are motivated to vote after 2 terms of a president they don't like from the other party? Maybe we should switch to one 6 year term. The first year is a learning curve. The last year is campaigning. Maybe the country would be better served with a different format. What do you think?