When you are dealing with a service like gamepass, you need 2 games at a month. You are dealing with people who have different taste.
Playstation devs only worried about the ps5 and maybe ps4 version. So they put out games fast. While on xbox side, they take time. Unlike the other guys, their games are mostly taxed and long. God of war is short and on point. Forza horizon 4 isn't.
Its why you can play xbox games longer, while Playstation games shorter. One is small and on point, while the other is complex and have different branches(Skyrim, fable, new halo).
With their 23 dev output, they will need to have 4 projects per studio to do it. Or else get new studios, or build new ones from ground up for other ips (rare ip, betheseda ip).