Personally I'm ok with having only the option to win one time with the lottery. I have a friend who has been trying since 2005 to get a permit via the lottery and has had to rely on cancellations or walk-ins.
If limiting the lottery to one win per group leader leads to more people winning spots im all for it.
If you want to go more than once then I think its fair to wait for cancellations or do walk in.
Just my 2¢
