I agree with Clay.  The green is for nailing lines and feeling good about it.  What I said about Ravens still holds true...  Odds are you will be there with somebody who knows it, at least a little.  I have paddled in South America and out West where I didn't know the lines... Yeah scouting lines for yourself develops the skills to paddle any river, but the question was preparation.  Nailing lines is key, whether you pick them or your crew points them out.  So for the SE runs being able to nail lines on the Green, such as the big three, left line at sunshine, gorilla at 200% etc. will tell you whether or not you can make the moves necessary to run the shit, but like Clay says, it comes down to your ability to size something up and make the decision yourself.