Correct me if I am wrong, but a truly great course will continue to show golfers new nuances for years and years. Remember Mackenzie's comments on The Old Course.
Therefore, raters/panelists shouldn't be overly concerned with only playing a course once as playing it again won't yield that much more information.
But here is the kicker, I think you have to do a fair amount of due diligence on a course prior to playing it and take meticulous notes while playing it to get the most out of a single play. Simply showing up, playing course x, running over to course y, and then getting up at zero dark thirty to make it to course z isn't going to cut it.
As goofy as this sounds, I try to do a fair amount of research on the course before hand to understand what I am about to play, pay attention as I play it, and then have a personal de-brief with myself after the round to try to comprehend what I just saw and truly understand what the architect was trying to do and if he, indeed, did it.
In my opinion, that is how you get the most out of a single play.