Problem goes back to the Constitution and lack of clear text on ‘numbers’.
I would say this...if we go to ‘11’....why settle on that number being the ‘end’?
You might as well double down and say it should be 50 judges (1 from each state, with the judge required to have residence in his home state), and you draw a random 7 or 9 judges from the hat each time a case comes up. I’d even go as far as having each state (not the President or the House) determine their state supreme court judge.
The ability to “pack” the Supreme Court is a “hole” in the Constitution that needs to be plugged. I would definitely favor an amendment capping the number of judges at nine.