I have tried a mix of drones. The larger ones do the bulk of the work and when the asteroid is down to the last 1,500-2,000 blocks I deploy a couple of my original 5x5x5 drones that can tuck in better and pick off the single blocks better than their larger conterparts.
I too sometimes employ a salvager that carries drones in order to make light work of a field.
I too sometimes employ a salvager that carries drones in order to make light work of a field.