I'm not quite sure where the whole "Otz always has an 8-man rotation" idea came from (it's not just you; pretty much everyone says it), but I don't think it's very accurate. Here are some of the top-line minutes numbers in Big 12 play from the Otz era:
2021-22: 8 guys played in 16 or more games, all averaging 12+ minutes a game. Tre Jackson played in 11 games, averaging 13 minutes, and Jaden Walker played in 10, averaging 10 minutes.
2022-23: Injuries and Grill's situation made this one odd, but 8 guys played in 14+ games, all averaging 10+ minutes (Grill at 15 games and Watson at 14 games). Kunc played in 9, averaging 23 minutes in those games, and Ward played in 8, averaging 4 minutes in those games.
2023-24: Much more straightforward; 9 guys played in 17+ games, with Pav the only one below 10 minutes a game (Pav was at 7 minutes).
Last season was the first that didn't have 10 guys play in at least half of Big 12 games, though it had 9 guys play in almost every game of Big 12 play.
I think it's possible that Otz is moving towards limiting the rotation more now that the team is better skilled and less reliant on hustle and defensive effort. But, history shows that Otz is definitely willing to play more than 8 guys, especially while tinkering at the edges of the rotation. This is really the first season where it was clear before Big 12 play what his preferred rotation was.