Michigan and UConn both had 9 guys play >30% of their minutes on the season, though their rotations shrunk by the end (at least partly due to injury for UM).Measuring by total minutes is tricky because there's so much early season garbage time built in. That's why, when I think about our "real" rotation, I tend to focus on what the rotation looks like in conference. But yeah, ^ that's all true.
I think sometimes people think that having a 9th man who is a key cog in the rotation is a sign of a roster's strength. But I'd argue more often it means that one / some of your top five players aren't good enough to stay on the floor. Kinda related to the football adage "If you have two quarterbacks, you have none."
Among Torvik's top 10, Duke and Purdue had 9, while Houston had 9-10.
So it's certainly not a bad strategy to have 9+ guys who can contribute meaningfully over a season, even if it's just to keep your core fresh and/or to fill in for injuries.