This is actually a bit of a play on words but that is not really the intention here. What should you gun for? Will you go for efficiency or will you root for effectiveness?

You can visualise like this : eficiency is like the maid. She will do what she is told. May be, she will do the jobs a little quicker each time since she gains experience each time doing it. Effectiveness is like you. You would just not do things quicker but you would question whether to do it at all or to do something else.

Doing something better and faster and much cheaper is efficiency. Doing things so that the paradigm shifts is effectiveness.

Most time in life we try to do it efficiently. Sometimes, we simply have to go for effectiveness even at the cost of efficiency. If something can be dome more effectively, evne if it means sacrificing efficiency a little bit, it is worth it.