DMR fills a bulk chamber to a height of 2 to 2.2 metres, loaded so one square metre of tunnel floor carries about 900 to 1000 kg of compost. An even fill at that loading is what lets one blower serve the whole mass.
A deeper fill on the same floor raises resistance and the bottom compacts under its own weight. A shallow patch becomes the easy path for air. Level the surface by hand after the loader has finished, and check the height at several points rather than one.