I prefer the idea that there is no set number of justices, every president gets to appoint one judge per term. Obviously they should still be approved by the Senate. After the Senate approves the judge, that's it, someone dies, to bad wait a few years for the next term or president. Sure we might end up with 20 justices if a bunch of young people are appointed but that just opens up the term limit conversation, and that would be great since lifetime appointments shouldn't be a thing for any position.