I am a 7 year Adderall prescribed user. Let me just say that post above mine about work being awful without your daily dose...is true ×50. Now anyways. Let me just explain something. Adderall will get you very excited and motivated to do the work and will basically put you on auto-pilot. However if anyone has ever noticed adderall kind of makes time go by slower.
Look at your watch when you are intently focused and "high" on a dose of adderall. 20 minutes gone by in your mind may seem like 40, or up to an hour in some ridiculous cases.
Might I add though, when you are under the influence of the adderall you are not negatively affected by this. In fact you enjoy having a sense of infinite time whilst @ work. Hope this helps.