That's all well and good if the standard of work you expect is of a low standard. But if your standard is high then by rearing 2, 3 or even 4 pups together you've increased your chances of ending up with 1 or 2 good ones.A pup should know it's name and come when called before it enters a field and once in the field ,as a pup, it should be allowed to be a pup but still come when called.
Once they start to become saplings they should start to knuckle down and concentrate on their work.
JMHO.
PARK LIFE !