755 laser is Alexandrite safe on skin types I-III. On those skin types you need minimum of 16J on 18mm spot for permanent hair removal and ideally go up to 18J. 9J is waste of time and money.
She is only using 9j because she fears risks of burning you since type IV is darker skin for Alexandrite. I don’t know why she isn’t using ND:Yag laser which GentleMax offers and designed for darker skin types.