If a group of friends serve their time in the army, the only thing they’re guaranteed is that they’ll get out at the same time (barring wartime risks, etc). Not that they’ll serve together. Now, that makes a certain amount of sense for a band to arrange things so that they’ll all come back at the same time.
But proposing that they be kept together for PR purposes-- that the army give them special treatment-- that would involve the cooperation of people who might not be fans, who might resent being told what to do with conscript labor. They might be kept together for PR purposes, they might be split up to avoid favoritism.
