Staff Corps, Limited Duty, Direct Commission, and really any classification of officer for the US that was not expected to be a 'War Fighter" or in direct support have traditionally had more abbreviated training regimens that also did tend to be less intense. In part this was from the obvious, that their main qualifications and skills were earned previous to their entering service, and partly to keep service an attractive option and the pipeline moving quickly for valuable subject matter experts.

The modern scheme which emerged post Vietnam essentially allows Staff Corps Officers to bypass basic Officer Candidate School(OCS) or any previous ROTC or Academy time and jump to the next phase. This is what is known as Basic Officer's Leadership Course or BOLC(pronounced Bowl-ick), this is where most of an officer's actual professional training in how to operate in Big Army occurs. While OCS is mostly about indoctrinating the officer candidates into how to think as an officer and leader, follow orders, act as a team, and screen out those not physically or mentally up to snuff. So for Staff or other officers then you can add in some marching, some PT, some learning things like rank recognition, and the organization of their future commands as a shorter program. An Army Doctor is never going to need to lead a platoon in close order drill, or conduct a patrol, so while exercises like that have a certain value (even before they are officially taught the Army way then as stress, teamwork, and leadership tests) so you don't need to be spending as much time on it. While an Army Chaplin doesn't have a pressing need to have expert level land nav skills either as another example of stuff that if present is nowhere to the same depth.

All the branches then have some slight variations, the Navy then instead of a BLOC system has a far different officer training pipeline. So they run their Officer Candidate School out of Newport and alongside have Officer Development School for their Staff and Restricted Line Officers. Its both shorter and less "in your face" being 5 weeks vs 12 for OCS. From there newly minted officers could end up at either follow on training of their first commands.