I'm pretty sure the 7th Cookout (2012) had 20 holes. I did not play the 8th (2013) so I can't verify how many there were last year (though I was always curious).
Another reason why the 2012 cookout may have atypical results: 1st round for intermediate had a funky OB rule. I played advanced so I'm not 100%, but I think the rule was "if you go 'long-grass-OB', but not real OB, you get to take the disc back to where it went out without penalty."
Then in the second round that rule was removed and all long grass was OB. So the scores jumped up big time the second round.