I agree with this.

When you apply aileron the down going aileron produces more lift and the penalty is more drag.

The opposite wing has an aileron that moves up, resulting in less lift and less drag.

If one wing has more drag than the other it causes yaw. In this case it is called 'adverse yaw'

The rudder can be used to compensate for this adverse yaw. By applying rudder in the same direction as the aileron application.

Note that adverse yaw is a function of aileron deflection, not angle of bank. IE you only need to apply rudder while your ailerons are deflected.

This will produce a 'coordinated turn'. If you were in a real aircraft. You would see the balance ball is centred if you apply the correct amount of rudder to compensate adverse yaw.

There are many factors affecting the amount of adverse yaw in a given aircraft design, wing span, wing profile, use of differential or Frise ailerons.

I agree there are many situations where you may want to fly out of balance to achieve a specific objective, eg, thermalling, turning with minimal bank, or side slipping in a crosswind, or aerobatics.

For normal flight, use of rudder will improve your turns by eliminating adverse yaw.

Plenty of good reading if you google 'secondary effect of flight controls'

http://youtu.be/NXMwvEx56Gs