I think if we combine a few posts here we have the gist of it:
4 "slots" every 12 hours
8 slot Leve History that can be turned in for an evaluation, thus giving you a boosted leve.
Upon clearing/failing a leve, your "Available Leve" list is updated, thus granting you an "unlimited" list of leves, just a limited amount of tries.

Did I miss anything? So basically, if you HAVE saved up (hypothetically) 99 leve "tries", you can do as many as you have "tries" for. The list keeps updating based on your completion.

SE has a chance to really make this a good system. What we don't need is a large "leve slot stock" and can only do the same leve once (unless failed and retried). Fortunately, it doesn't seem like they're going that route, unless they create a whole slew of new leves per Camp. A Dev post would really help us out here