Many people choose to do things efficiently, because they probably assume that it is the best way to be successful and that it is the best way to get the highest value with the least amount of effort. But substituting efficiency for effectiveness makes things worse instead of better. The fact is that efficiency and effectiveness are two different things. Someone can be incredibly efficient, without being effective.
"Balls can be cut in half, so that more balls fit in the package. Very efficient, but not effective, because the balls loose their purpose."
"Surgery can be performed very efficiently, but is very ineffective if the patient dies."
"Formula racing teams would be able to race very efficiently and thereby even save costs on damage, fuel and tires. But then they probably come in last with 20 laps or more behind."
So the way I look at it is:
Of course efficiency is important and of course it is good to see if you can do things more efficient, but only if effectiveness remains the same or increases.
In 1994 Dr. Russell L. Ackoff already said "The difference between efficiency and effectiveness is the difference between knowledge and wisdom." (Source: Youtube).
So be careful, use your wisdom and don't fall into the efficiency trap.