In S5E8, Hank talks about the job he had when he was on college and implies how simple, but easy the life was back then to Walt. Why that job is selected as the college job of Hank by the writers? Why not delivering newspapers for example? Is there a symbolism/metaphor here?
Oh, yeah? Back in college, I'd spend my days marking trees in the woods with this-- this orange spray can.
Crews would come in later and find the trees I tagged and cut them down.
First, you go in, and you mark locations for skid trails and landings. Then you choose specific trees all within a selected grid. (Script source: springfieldspringfield)
Now if you read it attentively you will notice he said orange spray and what other orange prominent thing was in that episode? "Prison uniform", Hank and DEA has marked those people orange too who get killed. Same fate as the tree. So this tree tagging story is just a parallel to what happen to the prisoners.
Same was concluded by ew.com too.