Yeah Lt. Col is fairly easy to reach if you "do your time". Colonel is much more difficult and requires a bit of luck and General is impossible unless you have General friends (seriously, you'll never make general unless another general grooms you and vouches for you)
He did make an unnecessarily-specific statement about being a lt. colonel at one point, but I don't know that it's a hard rank to get to. I though it was more the point at which career officers got stuck.