Sometimes a doctor will titrate you up until no further benefit is seen, then back the dose down to the lowest effective dose. This ensures that the most benefit is achieved. Some people cannot tell when they are getting optimal benefits because they have notthing to compare with.
This dose optimization schema is not usually taken with kids, who cannot be as active in optimizing med dose and the obsevations of others (parents and teachers) is used.
Remember... If you are just starting out and taking and stimulant med, to take the LOWEST EFFECTIVE DOSE. If 5 mg of lets say Adderall is working... be you're OWN doctor and say ok, this is fine for me and its managing my symptoms. You know your own body, a doctor may want to start you out there and increase but if it's working, tell your doctor that it is fine! just some advice!