More info:
Only one of your applications can be successful. It will not necessarily be the first application you created, since the applications are processed in random order.
If one of the applications is awarded, all the others are automatically marked as unsuccessful. If you really want a single specific date to start your hike, you can make multiple entries (at $6 each), and you can designate the most desired date as your first choice on each entry. The more entries you make, the better chance you have that one of them will be processed earlier in the lottery, and the earlier ones will have a higher success rate.
If you sign up as a different user with a different email address, or have others in your group sign on and enter the lottery, you MAY win several trips, and more than one could be for the same date if that is how you entered. Each entry will cost you $6, but if several win the same date, you can decline all but one, and only be charged the $15 per hiker fee for the one you accept.
Group size: If you ask for a larger group size (up to 15 is allowed), you might be less successful. This is due to dates filling up, and if your application is processed after some are nearly full, if your group is large, it would put the slots over the quota for the specific day. So smaller group sizes have a better chance of winning a reservation.
