The lad obviously doesnt know much about mole trapping. duffus are easiest set on a shallow run, with a light coating of soil on top.I too set duffus well deep but couldnt be arsed saying not to set it a foot deep , but not to cover it with a foot of soil as it might not spring with sufficient force to kill said mole . Thats why, for easyness i said duffus for shallow.
If he sticks to duffus for shallow, scissors for deep he wont go far wrong.