I don't think that when we pull it we are getting the true length.
In order for your hair to be at the length that it is when you pull it, it would have to be stick straight like typical Asian type hair and be heavy enough to stretch out to it's complete length.
Sorta like a rubber band. It is a certain length, but when streched it's longer. It can't be at it's strecthed length without something pulling on it.