PRESSING BUTTONS DOES ABSOLUTELY NOTHING!!! It's just a rumor that is as absurd sounding as yelling into the DS mic to increase the chances of catching a Pokemon or waking up...
But I can't help but find myself doing it out of habit, even though I know that it doesn't work. Just gives me that false sense of confidence. When it "didn't work", I just tell myself that I didn't press it at the right time. Basically, it "works" because you make yourself think that it worked. IMO, anyway.