I’m also confused about this. I am currently ups to 90mg vyvanse which is higher than most drs will prescribe. But my doctor (and also confirmed by Dr. Hallowell) say that it is ok to go higher, that some people just need more for whatever reason. You can monitor blood pressure and heart rate daily to make sure that they don’t increase too much as you increase the dosage. I’ve been told that going up as high as 110-120 mg would be safe and if I still don’t notice benefits at that point then to change to a different medicine.
At all dosages up until 80 mg I didn’t experience any positive effects.
The only negative side effect I have experienced is very dry mouth. I think it helps me generally but the benefits are indeed very subtle at this point. I know I feel better but I can’t really quantify the effects on ability to focus or productivity etc.