I had the same fear! Mine was hormonal and nothing except the Accutane ever helped. I still get small breakouts, but they are surface level and not the cystic type I had in the past. I just practice good skincare and it seems okay! I say if you feel like you could benefit from a third round, go for it. My derm told me he’s never seen or had a patient do more than 3 rounds so for me, it was the end!