d-amphetamine will never be a problem as long as you tell yourself every time before you take it "this is just amphetamine and everything i do or think in the next 12 hours is influenced by amphetamine and I should take all of it with a grain of salt" and then strap in for the ride. The biggest mistake an amphetamine user can make is taking it like they're smoking a fucking cigarette with no thought or concern put into it; you will wind up psychotic very very fast like that. And if you're so burnt out you lose the willpower to even check yourself to see if you've got to that point, you're already at that point and should go to sleep