In the mid-1800s, Senators from Vermont & Massachusetts introduced legislation to expand the Supreme Court to 15 Justices, but only 7 would be randomly selected to sit in Washington to adjudicate Supreme Court cases; the rest would ride circuit, sitting primarily as trial judges
It was a stupid idea and the Senate decisively rejected the proposal, but from what I've seen no one suggested it risked creating a "constitutional crisis" as either side almost certainly would declare today, if the other advanced the notion.
Throughout much of the 19th century, appeals from federal district courts were to circuit courts, staffed by a single judge, who often was the same district judge who issued the ruling under appeal! Circuit court appeals often wound up being more like motions for reconsideration
