It's a quirk of the TOPS system and freight trains vs passenger trains - multiple unit schedules are designed to be used by passenger operators using a different computer system (GENIUS or whatever it's current incarnation is).
This is a picture of a trial train in the parcels platform at Daventry which ran a week or so before the service started up (scroll down the article a bit) - https://www.bbc.com/news/uk-england-northamptonshire-66069338
You may notice the lack of wires... the 325s are apparently hauled from the reception sidings down the branch by the resident shunter, so arguably it's kind of loco-hauled although not on NR metals. I assume the loco used is this one pictured shunting the DC420 warehouse, perhaps someone can confirm the current shunter(s) in use at Daventry - https://www.flickr.com/photos/steam60163/51493178666/
1S05 pictured passing Warrington on Tuesday - https://www.flickr.com/photos/121541544@N07/53123430900/in/photolist-2oWktdq
This 2022 drone footage starts by looking towards the new Royal Mail facility and gives an idea of the distance from the reception sidings (about 2 miles I believe). It also gives a good view of the Russells terminal (with the overhead gantries) next to the Sainsburys warehouse (neither of these videos or pictures are mine by the way):
YouTube: Daventry Rail Freight Terminal 2022 | Anything Transport
On YouTube there's also a cab view down the branch as far as the Russells terminal (admittedly in the dark but the junctions are lit up). Timestamps: departs from reception sidings 6:45, passes the entrance to the Stobarts / Tesco container terminal 10:55, passes the junction for the DC420 warehouse 15:45, enters Russells / Sainsburys container terminal 21:00 then returns light engine to the Malcolms container terminal next to the reception sidings. If it had continued down the branch past the Sainsburys terminal, it would have crossed the bridge visible in the drone footage and ended up at the Royal Mail facility.
YouTube: Daventry | The Prop
Is there any news on the construction of or any plans to use the other rail facilities on the new site?