The hydrogen in $\ce{C4}$, $\ce{C6}$, $\ce{C10}$ and $\ce{C8}$ belong to same hydrogen environment.
The hydrogen in $\ce{C3}$, $\ce{C1}$, $\ce{C11}$ and $\ce{C13}$ belong to the another hydrogen environment.
Hydrogen in $\ce{C12}$ and $\ce{C2}$ belong to the once again, another hydrogen environment.

My question is $\ce{C3}$, $\ce{C1}$ , $\ce{C11}$ $\ce{C13}$, $\ce{C12}$ and $\ce{C2}$ all have two hydrogen in the neighboring carbon atoms. So why aren't they classified as one hydrogen environment? Instead why are the categorized under two different environments? Answer needed as soon as possible please.