7 months. You can keep making gains, no matter how long your cycle is, just so long as you regularly change your steroid combinations. I didn't have any notable side-effects from doing a 7 month cycle.
I recently finished this 7 month cycle and have been on clomid therapy for almost 5 weeks now. My sex drive hasn't returned and I am worried that my natural testosterone production may have been permanently impaired. I don't know whether or not this is in my own head. People have scared me by their talk of long cycles and permanent test suppression.
Because I am having trouble getting my nat. test production back I won't be doing any more long cycles. I will limit them to 12-13 weeks from now on. But if you want to do long cycles, it is possible to keep making gains.