If an excavation is digging over a couple meters downwards, archaeologists often alter their approach.  Box-grids will not function well for deep excavations because they are usually too small and the walls are in very real danger of caving in on someone.  Yet an archaeologists also will not excavate an open-area trench more than a few meters either, often due to issues getting back out, similar issues of collapse, and the sheer magnitude of excavation that would need to be done. 

Every excavation is different, but we have the experience and equipment at ADS Services.