Myth or Truth???
Go to any box and reset it (11) times. Buy 1 single pack. Reset it again 11 times. Buy one single pack. Repeat process 3-5 times and more likely than not you will have pulled out 3-5 SR/UR.
Note: do not reset a box you may regret later. Conduct the experiment on a box that is new or that you would not care resetting.