The route will loose a bit of its attraction if the crossing time was shortened, as 24 hours on the ship counts as a driver’s weekly rest break. This resets their week and allows a full week’s work when they get off in Dunkirk.
A lot of drivers stay in their cabs on the longer Irish crossings. You can normally get up have your meal in the drivers restaurant and get back down again before the doors are locked. Not legal I know but it’s what happens. On the short crossing most use the cabin for a shower and sit in the drivers lounge.