Compare pictures $1,4,$ and $5.$ These three pieces of blacktop road are within a mile of each other, and have experienced similar traffic $($except that after $5$ fell apart, people quit driving on it$).$ A really good hypothesis based on these is that:

Blacktop is like fine wine$-$the older it is$,$ the better it is$.$

Blacktop is like a diamond, and doesn't change enough to notice with the passing of a few decades.

Blacktop is like leftovers in the refrigerator$-$the older it is$,$ the worse it is