I am prescribed d-amphetamine instant release tablets, also known as dexedrine IR. IME, This doesnt build a tolerance as quickly as adderall does (as two of the four salts of adderall are racemic amphetamine, and the other two are d-amphetamine).
You could definitely use it once a week to once a month, although you might still want to try out lower dosages. Often I find a similar medicinal effect can be achieved without getting to a similar degree of side effects.
Make sure to continue to focus on eating well, drinking plenty of water, and using mineral supplements as well as taking vitamins.