I think that's too lenient. I'd expect more games per quarter (not just one per quarter) and sooner than 2024. Even if we take out Zenimax and Activision (has to) studios for now, XGS had the same amount of studios as PlayStation since 2018, right? (~ 13 studios).
Sometime ago,
I analyzed PlayStation games exclusive output, which showed that PlayStation has been already doing for years what Xbox plans to do in the future -- to release on big game per quarter. It just goes under the radar.
Even if some disagree with some of the games I put there in the 'big games' category (which is totally fine), the average still remains well under 1 game per quarter. As of now, per that analysis, PlayStation's output was 1 big game every 39 days -- in addition to many smaller AA exclusive games. Take out some of the games from the 'big' list, it'll still be 1 big game per 60 days.
Considering that Xbox will have twice the number of studios than PlayStation, I'd expect no less than 1 big AAA game per month from them. One big game per quarter is not enough, knowing that PlayStation has been doing it for years with less than half the studios.