GMC 2008 Yukon Denali Owner's Manual page 38

Q:
What is wrong with this?
A:
The shoulder belt is too loose. It will not give as
much protection this way.
1-34
CAUTION:
{
You can be seriously hurt if your shoulder belt
is too loose. In a crash, you would move
forward too much, which could increase injury.
The shoulder belt should fit snugly against
your body.