I remember having seen a default ratio of 5 for OSD/journal relations, meaning one SSD would be configured to hold journals for 5 OSDs. But this should not apply here.

Do you use different disk types? Are those physical servers and disks?

I have a small lab environment and tried to reproduce it with 9 disks per node (3 nodes in total). All 9 disks were proposed as standalone OSDs.
Do you have any traces of previous installations? Are all disks wiped before running the stages? You could run the stage with debug logs:

salt-run state.orch ceph.stage.<STAGE> --log-level=debug