Do you think that efficiency can conflict with effectiveness? Explain and provide many real live examples as you can.

Basically Efficiency and Effectiveness are two sides of a coin.
Efficiency is competency in performance or ability to accomplish a job with a minimum expenditure of time and effort while effectiveness to achieve the intended or expected result.

Ex. 1

In an advertising campaign. A company could spend millions of dollars on commercials and billboards to get a product out there. That example would be effective, but not efficient. That same company could make a silly viral video and "leak" it for free on the internet. That would be efficient. But the best way would be to balance between both approaches. That would be both efficient and effective.

Ex. 2
Suppose that two guys, X and Y, are trying to change a flat tire on their cars (each one has his own car).
X starts by taking out the jack and placing it under the car. He quite doesn’t know where to position it, so he goes by trial and error and wastes a lot of time doing it. After 30 minutes he finally manages to fix it, so he proceeds to lift the car and change the tire.
As you can see X was doing the right thing, but he was doing it poorly. We can say that he was being effective, but not efficient.
Y, on the other hand, starts by grabbing a towel and cleaning the tire. He wants to make the thing shiny before he changes it. And mind you he is very good and fast at cleaning every little detail of the tire.
We can say that Y is being efficient, because he is cleaning the tire fast and thoroughly, but he is not being effective, because cleaning is a step that is not required at all when changing a flat tire.
Now if we had a third person, Z, who could change the flat tire using the right steps and doing it quickly, we could say that he was both effective and efficient.

Ex. 3

Two different lathe operators, say A and B, are assigned the task of making wheel nuts on a lathe. Let us say A produces 100 wheel nuts in a shift, and in the process uses up 5 kilogram of steel rod in the process. In comparison, B produces 120 wheel nuts using 7.5 kilogram of steel rod.
The effectiveness and efficiency of these two lathe operators based on their performance is compared in table below:
Operator Effectiveness Efficiency
A 100 wheel nuts /shift 20 wheel nuts / Kg of Steel
B 120 wheel nuts / shift 16 wheel nuts / Kg of Steel
Now if we had a third person, C, who could produce 110 wheel nuts /shift at 18 wheel nuts /Kg of steel, we could say that he was both effective and efficient.

Ex.4

At Dunkin' Donuts in the us they train their employees to memorize the regular customers and their usual orders so they could recognize them from back of the line and ask them if they want their usual to save time and be efficient while at the same time serving customers faster and addressing them with their names increase customer satisfaction and that is effectiveness.

Conclusion

To answer the main question ; yes efficiency and effectiveness can conflict sometimes but through proper management and the wright training they can cohabit.