The less numbers you put on your ballot paper the better the chance that someone you would NEVER vote for gets up. We got such a ragtag bunch last time because people voted "1" above the line. Eventually someone nobody ever heard of showed on two major party's preferences and he/she was the lucky candidate.
Don't be lazy, number at least 6 above or 20 below the line. There will be no pattern in individuals' votes so there will be no Ricky Muir then.