Which is to imply that I don't?
I only take it regularly, so wtf would I know?
"Smart Drug" is about as accurate as saying you can get jacked taking steroids with a crap diet and no lifting.
As I said before, it increases alertness. It doesn't make you smarter, force you to have razor focus or some other abnormally increased brain function aside from keeping you from feeling lethargic. Yes, a secondary effect of being alert is the ability to focus better, but only if you choose to.
It does help me stay lean, which is nice, but that's because without it I'm in shutdown mode 75% of the day.