Yeah, sadly amphetamines are one molecule that your body gets really good at tolerating really quick... tolerance to the appetite suppressing and mood-enhancing effects of amphetamines develops very rapidly but tolerance to the waking-up and improved focus effects takes longer and never gets as bad. So you'll eventually be in the same mood and eat just like normal at 120mg/day, but you'll still be getting a sizable concentration boost & have difficulty sleeping if you take it at night.Well, that's what they say at least. I'm not gonna defend it either way. That is the justification behind it being a good medication for long-term ADHD treatment though; still, MrGuy's right: he could ask about switching things up if he wants after awhile, or not take it on the weekends at all; but you can just stick to one dose forever and keep getting benefits from it. If you play with it though & have fun, your tolerance will go up and then you'll lose the effect at your prescribed dose, basically. Which is why it's important to do what the doc says if you're smart and healthy and all that :)