A number of years ago I documented the construction of a manufactured home (from construction through placement) for a publication in Oregon. Before the clean-up step (which was before they sealed the halves up in plastic for delivery - the thing looked like a mess. Drywall dust everywhere, texture material splattered all over, you name it. This particular manufacturer had that clean-up step, and that crew got it looking really good for delivery.
Then the two halves were driven from Silverton, OR to Sherwood, OR - essentially a straight shot up I-5.
When it arrived, there were cracks in the drywall, damage to cabinets, and other issues that popped up in that relatively short road trip. But the finish crew fixed everything up very nicely. You'd never have known any of that damage was there.
The advantage that RV makers have is that it is essentially designed to be complete on leaving the factory, but many leave it up to the dealer to finish it out in terms of cleanup and issues. Grand Design is doing their own PDI and I would say it helps. The 385TH that was on display at the last RV show in Salt Lake City was really nice. All General RV had to do was clean it up a little more and it was ready for display. The fit and finish were far better than any of the others that we had considered (including Raptor, Voltage, Heartland, and even Tesla - although theirs was closer than any of the others). The folks at General RV said that, in general, there is less to get a Grand Design ready than pretty much anything else they sell.