Is it common for adult adhd patients to use stimulant meds only for short periods of time like a week or two when there's a greater need for focus? pros and cons of going on and off medication?

Depends on med: Many young adults quit treatments altogether because of the edgy way it makes them feel. The common stimulant meds like Adderall can be used episodically since because of the way they work (in/out within hours) others like Strattera require continuous use to have an effect (unless the effect is a placebo). With a valid prescription you can use it as needed, but you should discuss it with your doc