I don't know what happens in small POs, but in large ones, you'd best not be found reading magazines or opening mail. It would probably be dismissal. If they catch you opening/removing mail, the postal inspectors will come to you and arrest you. In spite of problems you might have, the US postal system is the best in the world, and very safe. Most of the torn up packages and envelopes are caused by customers putting too much weight into the package. I get loose stuff continually coming to me. It all gets sent to one work location and maybe they can match the envelope or package to the contents, or maybe they can't. Before you mail something, visualize it being churned down conveyor belts and falls and decide if you think it will survive this treatment. And ALL envelopes are BENT during processing. If your envelope can't be bent at least 45 degrees, you'd better put it into a package.
Just because you mark "fragile" on something doesn't mean a thing. You'd better pack it good. The post office isn't a bunch of old guys sitting around with visors on putting letters into boxes. It's AUTOMATION and mechanization.