Currently extension is taking 6-8 months. Yes it can get denied if you don’t give proper documents. Say your client changes with your extension pending and they give rfe asking for client letter, sow ,invoice etc., then you have nothing in your hand to submit and it can get rejected. I have gone through the situation. So, just after project ended I upgraded to premium. But it was too late because they put RFE and I hardly had anything to respond. They put second rfe and loosing all hopes I returned back to India because I was waiting for approval for 1.5 months (in bench because I cannot relocate when I94 expired and extension pending) and lost all hopes. Luckily in second RFE they asked only for previous LCAs and not client letter or invoice. Soo, finally got approved . Its advisible to do in premium if you don’t know how long your position will be there. I had no idea that my project will scrap due to budget cruch at client end.