12 years would be more reasonable. After 12 years, you are no longer a “people “. You have become a member of the ruling elite. Why do you think George Washington stepped down after two terms? Lifelong politicians is akin to monarchy rule for life.
Biden, Pelosi, Schumer, McConnell, and many others have shown that these people are not in office for the benefit of the American people, but for their own ambitions for power and wealth.