In that case you mean option -x not -z. Either way, there are several philosophies and schools of thought. Many of them yield good results in different situati

In that case you mean option -x not -z. Either way, there are several philosophies and schools of thought. Many of them yield good results in different situations. "Do one thing..." is not the same as "do _only_ one thing..." and there are exceptions to the rules and _we_ made the rules so _we_ can/may change them. Sticking to rules when they don't make sense is stubbornness and locks one in a local maximum.