Most of us have ruined a project by driving a screw half an inch too deep into drywall or snapping the head right off a brass fastener. It is easy to blame a cheap screw or an overeager trigger finger, but most of the time the problem is the collar right behind the chuck that you've been ignoring. I once added a wooden beam to my bed for extra support, and I had to buy a new beam because I didn't realize how important the clutch was. Once you know how that collar works, you'll have a lot more control over your drill, and it could save you a lot of money.