I have been critical as any of Russ and also would chuckle when I would hear about how he was the first guy in, last guy out. It was beyond me what he was working on so hard that he never improved the cerebral part of his game. However, to give him his credit, he is incredibly accurate (when he actually decides to throw) and showed improvement in accuracy over the course of his career. If you go back and watch his first 4 or so years in the League, he wasn't nearly the deep ball passer he became by year 7. He would toss em deep but many were the contested jump ball variety that he would rely on Rice, ADB or Kearse to grab down. Now he probably wasn't practicing deep balls in the QB room at 5am, but I don't think it was all entirely improv when he would break pocket and run around. He, Doug, Tyler and Kearse had a mind meld that I am sure in no small part was a result of him putting in the time to figure out the strategy of where he might reliably get the ball to after a receiver ran out his route, or where he might coordinate with a wr on where to be, say on a route that he figured would have a low probability of him making 'on time' (ie throws to the short and medium middle of the field). When he was best, we was rolling with guys he had worked with and who he knew well - guys he had put the time into watching film, understanding the playbook, and scheming the 'Russ' version of the play.
I am pretty sure he always knew he wouldn't be the elite x's and o's QB. He spent his hours figuring out how to succeed despite not having that ability. Seeing as how nobody ever succeeded at it the way he did, I'd wager he was genuinely working hard at it. It was just never a way of playing that would port anywhere else but Seattle under Pete. As soon as he HAD to play a straight-up QBs game, his days were numbered.