Unfortunately, no amount of "extra time" would have resulted in EJ becoming a good QB. Thats why he is on his couch now and most likely will not be in a lineup anymore.
Remember after Marrone, he effectively had a clean slate with Rex and yet couldn't win the starter position over Tyrod / Cassell. Beane and McDermott also didn't think highly of him so he didnt get re-signed. And neither did Chuckie...