This is far less about how often he’s fed, and entirely about how much would be fed at one time.
I fed once a day for 18-ish years. Why? Because nobody got more than a ration balancer, and there’s no need at all to split that.
I feed twice a day now and DO split that, for the sole reason my 33yo needs to eat at least 10lb of feed a day (and trying desperately to get him to finish that, let alone try to get to 12lb a day), and that cannot, should not be done in a single meal (not that he’d eat it anyway). So I bring them all in twice a day. If I could bring the 33yo in by himself to eat, and feed the others once a day, I’d do that in a heartbeat, but 33yo won’t eat at all if they others aren’t also there.