Beating the System (not really)

Do you ever get those surveys attached to your receipt where you get a coupon if you call the 1-800 number and give them your opinion? I get them every so often from Petsmart and Petco. Since I regularly shop at both stores, and $2-3 off my purchase helps I call the number. The surveys tend to be long and boring: “Press 5 if you were completely satisfied, press 4 if you were somewhat satisfied”, etc… But the last few I have called I go to press 4 or 5 in answer to the first question and bam! the mechanical voice gives me my validation code. Score! 2 dollars off my next purchase without spending 5 minutes pressing buttons on the phone. I feel a bit like I cheated the system, but really there is nothing I could do different.