You need to understand that @Stux is an “interesting” person.
Not only is he obsessed with traffic lights, but apparently he shops for HDDs at the local bath and beauty store. 
Click me for bathtub fun!
He’s referring to the “bathtub curve”, where the failure rate of HDDs is highest when brand new or very old, yet they’re relatively safe and stable in between. The graph looks like a bathtub. Therefor, the best drives to acquire are those that have enough lifetime hours to get them just past the “first side of the bathtub”, but not so old that they are on the “other side of the bathtub”.
