Would you recommend Accutane on regular or ultra-low dose?

I believe the proper dose of Accutane is 0.5 - 1 mg/kg per day for at least 20 weeks of continuous therapy.  This dosing is the most studied and published.

Usually the only time I put people on long-term, low doses is if they have already completed a full regimen. So I would do as your derm suggests and go with the 6 month regimen and then maybe go on a long-term dosage after that as a form of "maintenance". "This answer has been solicited without seeing this patient and
cannot be held as true medical advice, but only opinion. Seek in-person
treatment with a trained medical professional for appropriate care."