Why be concerned about shells with defective fuzes? Functioning fuzes present just as much of a concern and were the main reason for Air Raid warnings for the local populace.
Depending on the Mark of 3.7" gun, the rate of fire was between 10 to 25 rounds per minute. With each gun of a four gun Battery firing 20 rounds a minute of 28lb shell, the Battery is putting
1 TON of steel up in the air each minute. What goes up must come down. Typical building damage following an Air Raid included broken tile and slate rooves, broken windows, and damage to vehicles and livestock in the open. And that was without the Enemy dropping a single bomb.
I have some shrapnel pieces of 3.7" shell here, and even after 60 years the edges are razor sharp. If these were to fall on a building from 20,000ft, I'm sure they would shatter brickwork.