Is un/loading better with two narrow aisles or a single wider one? A single aisle takes up less fuselage volume.
Charging for a single bag has resulted in a contest to see how much stuff pax can waddle through the door.
So if you want to avoid being bogged in turnarounds, you may get faster results with baggage going into the hold than crammed under seats and overheads.
On many regional turboprops, the pax are invited to place their unchecked bags into a rolling bin on the tarmac just before boarding. Of course with 239 pax, that needs to be done at check-in.