Right, but launching a prospector 4km away and then having to wait for it to come back is even more wasteful, it's wasting far more real world time than just carrying more limpets by doubling the amount of time prospecting actions take because you have to wait the full recall time then send it to another rock.
It is far more convenient to just launch another one to a different target when you hit a dud rock.
It's a fair point. There's always having more prospectors as an option I guess, but it's something I hadn't quite considered.
Or, other plan: do away with prospector drones entirely... We can identify the make up of a planet from thousands of ls away with a pulse scan, why do we need a limpet to work out the material of a rock 4km away. Maybe some kind of scanner could handle that role instead