I've heard you're not supposed to stay on Accutane or Roaccutane for longer than about 6 months. When to Quit Accutane?

Ideally, Accutane should be administered for at least 5 months and there should not be much of any active acne cyst during the last month of administration and on some occasions, I have extended for a couple additional months, but never beyond 8 months. If you continue to have eruptions after being on Accutane for a year, one should consider other diagnosis such as recurrent MRSA (drug-resistant) skin infection. In addition, I would consider additional adjunctive therapy such as topical dapsone, PDT photodynamic therapy (Levulan with Blue light therapy x 4 in the hands of an experienced board-certified dermatologist who has extensive experience with PDT for acne 2-4 weeks apart) in addition to Oracea (low-dose submicrobial antibiotics) to achieve greater synergy and anti-inflammatory effect.

I would agree with Dr. Lupo. For a full course of Accutane, I generally do not have patients on the medication for longer than 6 months. The duration of the course should depend largely on the cumulative dose. It is standard to aim for a target dose of 120-150 mg/kg body weight for the full course of the medication.
Good luck.

Being on Accutane for over 6 months in one stretch is highly unusual. In over 25 years of prescribing, I have never done that and know of no dermatologist who does this. Please seek a new opinion for your care.