The production manager might perform personal inspections or oversee a group of quality-control workers. Routine preventive maintenance on manufacturing equipment can be important to avert potential standstills in production.
Toenails typically fall off due to either fungal infection or injury that results in a separation of the nail from the area of the toe called the nail bed, according to Foot Vitals. While pain is common with this type of injury, it is not guaranteed.
I'm not saying that it's completely normal, but that does not mean that it is not uncommon. I don't think that the reason your gerbil's tail fell off was because of the jagged area, but because your sister pulled him by the tail. You should NEVER do this. If you do, the tail will either deglove or just break off.