Consider an 18 year term limit for all Supreme Court Justices.

Thanks to life tenure, elections don’t have nearly as much consequence as they should have on the Supreme Court. A President might have zero vacancies to fill or may have many. Imagine each Justice was appointed to an 18-year term instead for life. With nine Justices, you would have a vacancy every two years. Every Presidential election would mean two vacancies at stake. A new President taking office in January would know that the first vacancy would come up a few months later in July, when the Supreme Court finished the work of its annual term. The second vacancy would come exactly two years later. Justices from previous times would cycle off the Court at predictable times, and they would be replaced by new Justices.
For the Supreme Court, elections would really have consequences.