Isn't Adderall used primarily in conjunction with other substances, though, to minimize aftereffects?
And I know people grind it up to snort, but I'm assuming that's if they can't get anything better. I can't imagine the absorption is effective through that route; I've heard Adderall referred to as a Johnson's Baby High.
I had a roommate who was heavily into Adderall and Ritalin, and she generally did it by itself. She stole it from kids she babysat, and forged prescriptions for it. It may have been because she "couldn't get anything better," but whatever drug she did was the best thing she could get on that day.